The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)

Muslim :: Book 35 : Hadith 6479

Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: None of you should say to Allah (like this): O Allah, grant me mercy, if thou so likest. The supplication (of his) should (be permeated with) conviction (that it would be accepted by the Lord), for Allah is the Doer of (everything) He likes to do, and there is none to force Him (to do or not to do this or that).