Sahih Muslim Book 33, Hadith Number 6425.

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.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: No child is born but upon Fitra. He then said. Recite: The nature made by Allah in which He created man, there is no altering of Allah’s nature; that is the right religion.”