Whoever comes to this world has to depart and therefore everyone suffers the loss of a dear and near person at some point in his or her life. One method of reducing the grief felt over that loss is to constantly benefit the deceased through Isal-Thawab, which means: to dedicate the reward of a particular nafl deed to someone; deceased or alive.

Isal-Thawab (to perform a virtuous act and dedicate the reward to any person, alive or deceased) is permissible and in fact (Mustahab) meritorious.
There are basically two forms of Isal-Thawab:

1. The conveying of the reward of (voluntary) charitable deeds.

2. The conveying of the reward of (voluntary) physical deeds that do not entail wealth, e.g. salat, fasting, dhikr, recitation of the holy Qur’an, tawaf of the Ka’abah, etc.

The first form is unanimously acceptable by the Ahlus Sunnah WalJama’ah. The second form is correct according to the Hanafi and Hanbali Madhab and several Shafi’i and Maliki scholars as well.
As for the reward of du’a (which is separate from the above), there is also unanimity of the scholars in its reward reaching and benefiting the deceased.(Refer Adhkar of Imam Nawawi)

Hafiz ibn al-Qayyim (rahimahullah) states that if one accepts the charitable form of Isal-Thawab and refutes the physical form, he should be asked: ‘What is the proof to show that the recitation of the holy Qur’an does not reach the deceased?’

Allamah Qurtubi says, ‘Just as the reward of charitable deeds benefit the deceased, similarly, the recitation of the holy Qur’an, Du’a and Istighfar (seeking forgiveness) also do the same, because all of these are regarded as sadaqah(charity) in Shari’ah.’ (Tazkirah, pg.71)

He thereafter mentioned two narrations recorded in Sahih Muslim which prove that even salat and dhikr of Allah (tasbih, takbir and tahlil) were all classified as sadaqah by Rasulullah (sallallahu’alayhi wasallam). Hence, there remains no dispute in whether the reward of Qur’anic recital benefits the deceased or not.

Besides the above, I will now for academic reasons, mention some proofs that substantiate both forms ofIsal-Thawab.

1. Rasulullah (sallallahu’alayhi wasallam) slaughtered sheep during his farewell Hajj and made intention for himself and all those (alive, deceased and to come) who bring faith on his prophethood. (Sahih Bukhari)

2. Imam Bukhari has reported on the authority of Sayyiduna ‘Abdullah ibn ‘Abbas (radiyallahu’anhu) that Sayyiduna Sa’d ibn Ubadah (radiyallahu’anhu) was away when his mother passed away. When he returned, he asked Rasulullah (sallallahu’alayhi wasallam), ‘Will it be of any benefit if I give charity on her behalf?’ Rasulullah (sallallahu’alayhi wasallam) replied in the affirmative. (Sahih Bukhari, Hadith: 2762)

Hafiz ibn Hajar al-‘Asqalani (rahimahullah) states in his monumental commentary of Sahih Bukhari entitled,‘Fathul Bari’, ‘this Hadith proves the permissibility of charity on behalf of the deceased and that the reward will reach him.’ (Fathul Bari vol.5 pg.477 Hadith: 2761)

3. Sayyiduna ‘Abdullah ibn ‘Abbas (radiyallahu’anhu) reports a man once asked Rasulullah (sallallahu’alayhi wasallam), ‘O Prophet of Allah! My father has passed away and he did not perform Hajj, can I perform Hajj on his behalf?’ Rasulullah (sallallahu’alayhi wasallam) enquired of him, ‘If your father had any debt, would you have paid it?’ The man replied, ‘Yes.’ Upon this, Rasulullah (sallallahu’alayhi wasallam) said, ‘In that case, the din of Allah has more right.’ (Sunan Nasa’i, Hadith: 26331).........
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