Sahih Al Bukhari – Book of Knowledge

Volumn 001, Book 003, Hadith Number 071. 
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Narated By Muawiya : I heard Allah's Apostle saying, "If Allah wants to do good to a person, He makes him comprehend the religion. I am just a distributor, but the grant is from Allah. (And remember) that this nation (true Muslims) will keep on following Allah's teachings strictly and they will not be harmed by any one going on a different path till Allah's order (Day of Judgment) is established." 

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