Sahih Muslim Book 33, Hadith Number 6423.
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.
There is none born but is created to his true nature (Islam). It is his parents who make him a Jew or a Christian or a Magian quite as beasts produce their young with their limbs perfect. Do you see anything deficient in them? Then he quoted the Qur’an. The nature made by Allah in which He has created men there is no altering of Allah’s creation; that is the right religion” (xxx. 33)