Sahih Bukhari
Sahih Bukhari Volume 008, Book 075, Hadith Number 350.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 75. Invocations
Narated By Anas : Allah's Apostle said, "When anyone of you appeal to Allah for something, he should ask with determination and should not say, 'O Allah, if You wish, give me.', for nobody can force Allah to do something against His Will.