Found the following article on Kalamullah, it's interesting.
The Islamic definition of Bid’ah:
Imaam Ash-Shaafi’i, may Allaah have mercy upon him, said: “A Bid’ah is anything that has no basis in the Qur’aan, Sunnah or sayings of any of the companions.”
Ibn Al-Jawzi, may Allaah have mercy upon him, said: “A Bid’ah is any form of worship that did not exist (at the time of the Prophet sallallaahu ‘alayhi wa sallam and his companions) then later it was innovated.”
Ibn Rajab, may Allaah have mercy upon him, said: “A Bid’ah is any form of worship which has no basis in the Sharee’ah which would warrant its legislation.”
Ash-Shaatibi, may Allaah have mercy upon him, said: “(A Bid’ah) is any matter which closely resembles the Sharee’ah and is intended to be a way of worshipping Allaah."
General rules to recognise Bid’ah:
1. Any act of worship is based on a fabricated Hadeeth is a Bid'ah, like the prayer in the month of Rajab which is called the prayer of Raghaa’ib.
2.Any act of worship which the Prophet sallallaahu ‘alayhi wa sallam did not perform, although there were no preventing factors is a Bid’ah, like uttering the intention before beginning the prayer, calling Adhaan for any prayer other than the five obligatory ones or praying after finishing Sa’y between mount Safaa and Marwah.
3. Any habitual act performed with the intention of pleasing Allaah which Islaam did not consider as an act or worship is a Bid'ah, such as for example: wearing coarse woollen clothes, continuous silence, refraining from eating bread or meat, not drinking cold water or standing in the sun.
4.Performing prohibitions acts with the intention of pleasing Allaah is a Bid'ah, such as singing songs about Him.
Moreover, all acts of worship must be performed in exactly the same manner as the Prophet sallallaahu ‘alayhi wa sallam did them. This cannot be achieved unless the following six conditions are fulfilled:
1. The act of worship must coincide with the Sharee’ah in the reason for which it is done, or else it would be rejected. Therefore, celebrating Al- Mawlid is a Bid’ah because it is performed as a
rewardable act, despite the fact that it has not been legislated.
2.The act of worship must coincide with the Sharee’ah in its category. Therefore, it is not acceptable if a person were to slaughter a horse instead of a camel or goat as a sacrifice after Hajj.
3. The act of worship must coincide with the Sharee’ah its quantity. Therefore, if somebody were to add two Rak’ah t o t h e Dhuhr prayer, making a total of six Rak'ah instead of four, this
would be unacceptable as it would not be coinciding with the Sharee’ah in its quantity.
4. The act of worship must coincide with the Sharee’ah in the manner in which it is performed. Therefore, if someone were to begin their wudoo' by washing their feet instead of their hands, then
this act would be unacceptable.
5. The act of worship must coincide with the Sharee’ah in the timing of its performance. Therefore, praying the Dhuhr prayer after sunset is unacceptable.
6. The act of worship must coincide with the Sharee’ah i n the place it which it is performed. Therefore, one cannot perform stand on a mountain other than ‘Arafah during Hajj.
The dangers of Bid’ah and their evil effects:
1. Bid’ah is a pre-cursor to disbelief.
2.Making unfounded statements on behalf of Allaah.
3.Correcting the Prophet sallallaahu ‘alayhi wa sallam or claiming that he had deficiencies.
4. Dividing the Muslim nation.
5. Abandoning the Sunnah.
6. Igniting disputes among the Muslims.
7. Accusing the Prophet of not completely conveying the message of Islaam.
8. Competing with the Prophets in their prophethood.
9. Altering the religion.
Claimed 'evidences' of the Innovators’ and their refutations:
Jareer Ibn ‘Abdullaah Al-Bujali may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “Whoever introduces a good practice in Islaam will get the reward of performing it and that of all those who perform it until the Day of Resurrection; Whoever introduces a bad practice in Islaam will get the punishment of performing it and that of all those
who do it until the Day of Resurrection.” (Muslim).
Refutation:
Imaam Ash-Shaatibi, may Allaah have mercy upon him, answered those who attempt to use this Hadeeth as evidence of the permissibility of innovating by saying: "Using this Hadeeth as an evidence (to innovate) implies that different evidences (Ahaadeeth) contradict one another (because in other Ahadeeth, the Prophet sallallaahu ‘alayhi wa sallam unequivocally warned against innovating)." Then he said: "The context of this Hadeeth is that it was said in a situation where charity was being given, and charity is something already legislated. The proof of this is actually to be found in the
very same Hadeeth, if you were to read it all, as
Jareer Ibn 'Abdullaah Al-Bujali, may Allaah be pleased with him, said: "We were with the Prophet sallallaahu ‘alayhi wa sallam (in the Masjid) just after dawn one day when some people entered barefooted and clad in woollen matting (or covered with sleeveless woollen blankets) with their swords hung around their necks. Most of them belonged to the tribe of Mudhar. The face of the Prophet sallallaahu ‘alayhi wa sallam turned pale due to their wretched condition. Then, the Prophet sallallaahu ‘alayhi wa sallam went into his house, re-emerged and commanded Bilaal to call the Adhaan, and the Iqaamah and then he sallallaahu ‘alayhi wa sallam led the prayer. After the prayer, the Prophet sallallaahu ‘alayhi wa sallam stood up and addressed people saying (that which translates as): “O mankind! Fear your Lord, who created you from one soul and created from it its mate and dispersed from both of them many men and women. And fear Allaah, through whom you ask one another, and the wombs. Indeed Allaah is ever, over you, an Observer.” (An-Nisaa’: 1) “O you who have believed! Fear Allaah. And let every soul look to what it has put forth for tomorrow – and fear Allaah. Indeed, Allaah is Acquainted with what you do.” (Al-Hashr: 18).
Then, the Prophet sallallaahu ‘alayhi wa sallam said: “Give in charity from (what you possess of) Deenaars (gold coins) Dirhams (silver coins) a Saa’ (a small measure of weight) of wheat or even a Saa’ of dates.” until he sallallaahu ‘alayhi wa sallam said: “Give, even if it as little as half a date” Thereupon, a man from the Ansaar (residents of Madeenah) came with a bag of food which was so heavy that it was difficult for him to carry. Thereafter, people came successively until I saw two huge piles of food and clothes, and the Prophet’s face was bright as a glittering golden coin (due to his happiness). Then the Messenger sallallaahu ‘alayhi wa sallam said: “Whoever introduces a good practice in Islaam will get the reward of performing it and that of all those who perform it until the Day of Resurrection; Whoever introduces a bad practice in Islaam will get the punishment of performing it and that of all those who do it until the Day of Resurrection.”" (Muslim).
Therefore, it is obvious that this Hadeeth refers to deeds that are already legislated and proven to already exist in the religion, which in this case was charity given by a certain companion of the Prophet sallallaahu ‘alayhi wasallam.
Claimed Evidence:
‘Umar ibn Al-Khattaab, may Allaah be pleased with him, remarked upon seeing people playing Taraaweeh in congregation that: "This is a good Bid’ah." (Bukhaari).
Refutation:
Imaam Ibn Rajab, may Allaah have mercy upon him, said: "Any words from the Salaf considering something as a good Bid’ah were meant in the linguistic and not the Islamic sense, such as the saying of ‘Umar, may Allaah be pleased with him, when he saw people praying Taraaweeh in congregation, that "This is a good Bid’ah.""
Claimed Evidence:
Ibn Mas’ood, may Allaah be pleased with him, said: "What the Muslims see as good is good in the sight of Allaah and what they see as bad is bad in the sight of Allaah." (Ahmad).
Refutation:
As-Sindi, may Allaah have mercy upon him said: "It is obvious that he was referring to the companions of the Prophet sallallaahu ‘alayhi wa sallam and he was talking exclusively about those things that they had a unanimous consensus on, it does not include others. This is besides the fact that these were the words of a companion and not the Prophet sallallaahu ‘alayhi wasallam."
Claimed Evidence:
Al-‘Izz Ibn ‘Abdus-Salaam, may Allaah have mercy upon him, divided Bid’ah into five categories: obligatory, recommended, permissible, disliked and prohibited.
Refutation:
Ash-Shaatibi, may Allaah have mercy upon him, said: "This categorisation of Bid’ah is something new which has no supportive evidence to it, moreover, it contradicts the definition of Bid’ah, because any deed which has an evidence which legislates it to be obligatory, recommended or allowed is by definition not an innovation, and it would have been included in the general recommendation of good deeds. Therefore, considering a matter to be a Bid’ah yet claiming the existence of an evidence to recommend it is a contradiction in terms."
Reasons behind innovations:
Ignorance of the religion of Islaam.
Following ones whims.
Clinging to doubts.
The sole use of ration with no reference to the Islamic texts (Qur'aan and Sunnah).
Islamic Scholars not fulfilling their expected role.
Dependence on weak or fabricated Ahaadeeth
Extreme reactions to others errors
The failure to limit ones understanding of the Islamic texts to that of the companions of the Prophet sallallaahu ‘alayhi wa sallam.
Blind imitation of the masses
Not following the instructions of sincere scholars.
Ways to eradicate Bid’ah:
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1.Warning against the dangers of Bid’ah a nd its evil effects.
2.Calling people to adhere to the Qur’aan and Sunnah,with the understanding of the Salaf.
3. Distinguishing between weak and the authentic Ahaadeeth.
4.Purifying the schools of jurisprudence from the innovation of fanaticism towards them.
5. Spreading knowledge and correcting the peoples understanding of faith, worship and financialtransactions.
6. Warning against and subduing the innovators
7.Receiving knowledge from the correct sources; i.e., the sincere guided Islamic scholars.
Related Qur’anic verses:
Allaah says that which translates as: “And do not be like those who became divided and differed after the clear proofs had come to them. And they will have a great punishment.” (Aal ‘Imraan: 105). Al-Qurtubi, may Allaah have mercy upon him, said: "This verse refers to the Jews and the Christians according to the majority of the scholars, but others have said that it refers to innovators within the Muslim nation."
Allaah says that which translates as: “On the Day [some] faces will turn white and [some] faces will turn black, [to them it will be said]: 'Did you disbelieve [i.e., reject faith] after your belief? Then taste the punishment for what you used to reject.'” (Aal ‘Imraan: 106). Ibn ‘Abbaas, may Allaah be pleased with him, said concerning this verse: "The faces of the people who adhered to the Sunnah will turn white and bright, while the faces of the innovators will turn black and gloomy". Al-Qurtubi, may Allaah have mercy upon him, said: "He who innovates or changes anything of the religion of Allaah will be amongst the black faced people who will be prevented from reaching the Prophet’s fountain and therefore prohibited from drinking from it".
Allaah says that which translates as: “And whoever opposes the Messenger after guidance has become clear to him and follows other than the way of the believers – We will give him what he has taken [i.e., make him responsible for his choice] and drive him into Hell, and evil it is as a destination.” (An-Nisaa’: 115). Imaam Ibn Katheer, may Allaah have mercy upon him, said concerning this verse: "This refers to those who take a path other than the one which the Messenger sallallaahu ‘alayhi wa sallam came with; so they became on one side and the Sharee’ah on the other, despite the fact that the truth had become clear to them and they knew this."
Allaah says that which translates as: “…This day I have perfected for you your religion and completed My favour upon you and have approved for you Islaam as a religion…” (Al-Maa’idah: 3). Imaam Maalik, may Allaah have mercy upon him, said concerning this verse: "He who innovates a new Bid’ah in Islaam considering it to be something good is in effect claiming that Muhammad sallallaahu ‘alayhi wa sallam did not fully convey the message of Islaam… So whatever was not a part of the religion at that time (i.e., the time of the Prophet and his companions) cannot be considered as a
part of the religion today." Imaam Ibn Katheer, may Allaah have mercy upon him, said: "One of the greatest bounties from Allaah upon the Muslim nation is that He completed and perfected the religion of Islaam for them, so they have no need of any other religion or Prophet other than their Prophet.
This is precisely why Allaah made Muhammad sallallaahu ‘alayhi wa sallam the seal of all Prophets and sent him to the Jinn as well as mankind. The only matters which are lawful are those that the Messenger sallallaahu ‘alayhi wa sallam made lawful and the only matters which are unlawful are those which he made unlawful. The only things that can be considered as part of the religion of Islaam are those which he conveyed; and that which he did not convey can never and will never be part of the religion. Everything that the Messenger sallallaahu ‘alayhi wa sallam said was true and correct without even a trace of error or dishonesty."
Allaah says that which translates as: “And [Moreover], this is my path. Which is straight, so follow it; and do not follow [other] ways, for you will be separated from His way. This has He instructed you so that you may become righteous.” (Al-An’aam: 153).
Mujaahid, may Allaah have mercy upon him, said concerning this verse: "The other ways mentioned are desires and innovations." Ibn Mas’ood, may Allaah be pleased with him, was asked about 'the straight path', he replied: "Muhammad sallallaahu ‘alayhi wa sallam left us standing at its beginning and it ends in Paradise. There are fast horses on its right and its left (indicating the speed with which they would lead one to Hell) with men inviting those who pass by (on the straight path) to come with them; so whoever responds to their invitation will be lead rapidly into the Hellfire, and whoever remains on the straight path will be lead to Paradise."
Allaah says that which translates as: “[They are] those whose effort is lost in worldly life, while they think they are doing well in work.” (Al-Kahf: 104) Imaam AtTabari, may Allaah have mercy upon him, said concerning this verse: "‘It refers to anyone who did an act thinking it to be correct and something that was in obedience to Allaah and something that pleased him, while in reality, it was a way of disobeying Allaah and straying away from the path of the believers."
Allaah says that which translates as: “So let those beware who dissent from his [i.e., the Prophet's] order lest trials strike them or a painful punishment.” (An- Noor: 63) Imaam Ibn Katheer, may Allaah have mercy upon him, said concerning this verse: "It refers to those who differ from the Prophet sallallaahu ‘alayhi wa sallam in any way, whether in his Sunnah, Sharee’ah or methodology. All words and deeds must be weighed according to his words and deeds, if they coincide then that is acceptable, otherwise, it will be rejected by Allaah regardless of who these words and deeds came
from, as the Prophet sallallaahu ‘alayhi wa sallam said: “He who does something which is not according to what we (i.e., the Prophet sallallaahu ‘alayhi wa sallam and his companions) are upon, then it is rejected (by Allaah)” (Muslim)."
Related Ahaadeeth:
Anas Ibn Maalik, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “Allaah does not accept the repentance of an innovator until he abandons his innovation” (At- Tabaraani & Bayhaqi). Sufyaan Ath-Thawri, may Allaah have mercy upon him, said: "An innovation is dearer to Satan than a sin, for one can easily repent from a sin, but an innovation is not easily repented from (as an innovator thinks that he is on the correct path)."
Al-‘Irbaadh Ibn saariyah, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “He who lives long enough will see many things which he will not recognise, therefore, hold on to my Sunnah and that of the rightly guided caliphs who succeed me; bite onto it (i.e., my Sunnah) with your molars. Stay away from innovations, because every innovation is misguidance.” (Ahmad & Abu Dawood)
Shaykh Al-Islaam Ibn Taymiyyah, may Allaah have mercy upon him, said: "Anyone who performs an act which is neither compulsory nor recommended, and intends for this to be an act of
worship, and believes it to be compulsory or recommended, is misguided and has innovated an evil Bid’ah according to the consensus of the Muslim scholars". Ibn Rajab, may Allaah have mercy upon him, said: "Anything newly introduced into the religion with no basis or reference in the Qur’aan or Sunnah is a misguidance, and the religion of Islaam has nothing to do with it."
‘Aa’ishah, may Allaah be pleased with her, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “He who does something which is not according to what we (i.e., the Prophet sallallaahu ‘alayhi wa sallam and hiscompanions) are upon then it is rejected.” (Bukhaari & Muslim). Ibn Rajab, may Allaah have mercy upon him, said: "Anyone who attempts to draw nearer to Allaah(i.e. please Him) by performing an act which neither Allaah nor His Messenger sallallaahu ‘alayhi wa sallam legislated as an act which pleases Allaah, will have that act rejected by Him."
‘Abdullaah Ibn Mas’ood, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “I will be ahead of you in reaching my fountain, and there will be people who will be prevented from reaching it, therefore, I will say: 'My Lord! These are my followers!' It will be said: 'You do not know what they innovated and altered after you.' (i.e., after your death) Therefore, I will say: 'Let those who altered (the religion) b e k e p t a w a y . (in a humiliated place).” (Bukhaari & Muslim).
‘Abdullaah Ibn ‘Amr Ibn Al-‘Aas, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “It was mandatory upon each of the Prophets who came before me to guide their nations to all that was good for them, and warn them against all that was evil for them” (Muslim). It was asked of Salmaan Al-Faarisi, may Allaah be pleased with him: "Your Prophet taught you everything, even what to do when using the toilet?" he replied: "Yes, he forbade us from facing the Qiblah (direction of prayer), and to clean ourselves afterwards using the right hand…"
(Muslim).
Abu Ad-Dardaa’, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “I swear by Allaah that I have left you with it (i.e., the religion) so clear that it is as clear at night as it is during the day (i.e., patently obvious) and only a doomed person will stray away from it.” (Ibn Maajah).
Abu Dharr, may Allaah be pleased with him, said: "The Prophet sallallaahu ‘alayhi wa sallam told us about everything before his death, even (something as seemingly insignificant as) the birds in the sky." (Ahmad). Ash-Shaatibi, may Allaah have mercy upon him, said: "From this narration, we know that there is no room for anybody’s opinion in matters of worship and that the only thing people must do is restrict themselves to the boundaries set by the Messenger sallallaahu ‘alayhi wa sallam."
‘Umar Ibn Al-Khattaab, may Allaah be pleased with him, narrated that the Prophet sallallaahu ‘alayhi wa sallam said: “Do not praise me (excessively) as the Christians praised ‘Eesaa the son of Maryam, I am but the slave of Allaah, so call me the slave and Messenger of Allaah” (Bukhaari).
Related words of the Salaf:
Ibn Mas’ood, may Allaah be pleased with him, said: "Follow (the Sunnah) and do not innovate, because you have been sufficed." (Ad-Daarimi). He also said: "Practicing a little of the Sunnah is far better than practicing many innovations." (Al-Haakim).
Hudhayfah Ibn Al-Yamaan, may Allaah be pleased with him, said: "Do not perform any act of worship which was not practiced by the companions of the Prophet sallallaahu ‘alayhi wa sallam because the early people (i.e. his companions) did not leave anything un addressed…so follow the way of those who were before you."
A man came to Ibn ‘Abbaas, may Allaah be pleased with him, and said: "Advise me" so he replied: "Fear Allaah, follow (the Sunnah) and do not innovate."
Al-Awzaa’i, may Allaah have mercy upon him, said: "Persevere on adherence to the Sunnah; stop where they (the companions of the Prophet sallallaahu ‘alayhi wa sallam) stopped; refrain from what they refrained from and follow the way of the Salaf because what sufficed them will suffice you."
Related stories:
Ibn ‘Abbaas, may Allaah be pleased with him, was circumambulating the Ka’bah with Mu’aawiyah Ibn Abu Sufyaan, may Allaah be pleased with him and his father, during Mu’aawiyah’s reign. Mu’aawiyah would touch all four corners of the Ka’bah while circumambulating and so Ibn ‘Abbaas remarked: "The Prophet only touched two corners (the black stone and the Yemeni corner)"
Mu’aawiyah replied: "No part of the house of Allaah should be neglected." Thereupon, Ibn ‘Abbaas recited (that which translates as): “There has certainly been for you in the Messenger of Allaah an excellent pattern (i.e., example to be followed) for anyone whose hope is in Allaah and the Last Day and [who] remembers Allaah often.” (Al-Ahzaab: 21). Upon hearing this, Mu’aawiyah refrained.
Sa’eed Ibn Al-Musayyib, may Allaah have mercy upon him, saw a man praying too many optional prayers before the Fajr prayer and therefore he forbade him from doing so. The man retorted: "O Abu Muhammad! Will Allaah punish me for praying?" Sa'eed replied: "No, but He will punish you for doing other than the Sunnah."
A man asked Imaam Maalik, may Allaah have mercy upon him: "At which point do I initiate my state of Ihraam?" he replied: "From Thul Hulayfah - where the Prophet sallallaahu ‘alayhi wa sallam did so" the man retorted: "I wish to do it from the area beside the grave of the Prophet sallallaahu ‘alayhi wa sallam" Imaam Maalik said: "Do not do that, for I fear that if you do so, you will be afflicted with trials" the man replied: "Why would I be afflicted with trials? All I wanted was to do it from a place which is only a few miles away from where you told me!" Imaam Maalik said upon hearing this:
"What can be more serious than feeling that you performed a righteous deed that the Prophet sallallaahu ‘alayhi wa sallam failed to do? I heard the saying of Allaah (which translates as): “So let those beware who dissent from his [i.e., the Prophet's] order lest trials strike them or a painful punishment.”"(An-Noor: 63)
Source:
http://www.kalamullah.com/Books/Bidah.pdf