A problem that results from the above hadith -- which seems to be the basis for the posters that are made of the ninety-nine names of Allah -- is that it contains some names which are not considered names of Allah. That is, ignoring this weak hadith, there is no authentic hadith or Quranic verse that offers evidence that those names are from the names of Allah. Since the names of Allah must be based on revelation from Allah (the Quran and Sunnah), if there is no authentic proof for specific names, they cannot be called one of the names of Allah. An example from the above hadith is the name al-Rasheed. There is no Quranic verse or authentic hadith that states this name. Hence, one cannot claim it as a name of Allah. Other commonly heard names that apparently are not from the names of Allah are al-Baqi, al-Sitaar and al-Naasir.
http://www.islaam.com/Article.aspx?id=67
Can we still proceed with memorizing these 99 names and leave out the ones that have no basis like the ones mentioned above^? Does anyone know of any place that has an authentic list of the Names of Allaah from the Qur'an and Sunnah?
هَلْ جَزَاء الْإِحْسَانِ إِلَّا الْإِحْسَانُ؟
Is there any reward for good other than good?
[ar-Rahman: 60]
"
However, keep in mind that you must instruct the people with kindness and mercy. Don’t take this answer and shove it in their faces. Be kind, gentle and patient." -
Imam Suhaib Webb, advising after giving an answer.
O Allah, Lord of Jibril, Mika'il and Israfil, Creator of the heavens and the earth, Knower of the unseen and the seen, You will judge between Your servants concerning that wherein they differ. Guide me with regard to that wherein there is dispute concerning the truth by Your leave, for You guide whomsoever You will to the straight path.
Oh Allah, I seek refuge in You lest I misguide others, or I am misguided by others, lest I cause others to err or I am caused to err, lest I abuse others or be abused, and lest I behave foolishly or meet with the foolishness of others.