Sahih Muslim Book 33, Hadith Number 6433.

Chapter : Everyone is born according to his true nature and the command pertaining to the demise of the children of the infidels and of the children of the Muslims.

Ibn Abbas reported that Allah’s Messenger (may peace be upon him) was asked about the children of the polytheists, whereupon he said: It is Allah alone Who knows what they would be doing according to their creation.