Sahih Muslim · Hadith 6929

حدثنا زهير بن حرب، حدثنا جرير، عن الأعمش، عن أبي صالح، عن أبي هريرة، قال قال رسول الله صلى الله عليه وسلم ‏"‏ ما من مولود إلا يلد على الفطرة فأبواه يهودانه وينصرانه ويشركانه ‏"‏ ‏.‏ فقال رجل يا رسول الله أرأيت لو مات قبل ذلك قال ‏"‏ الله أعلم بما كانوا عاملين ‏"‏ ‏.‏

Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: No babe is born but upon Fitra. It is his parents who make him a Jew or a Christian or a Polytheist. A person said: Allah's Messenger, what is your opinion if they were to die before that (before reaching the age of adolescence when they can distinguish between right and wrong)? He said: It is Allah alone Who knows what they would be doing.

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).