'Abu Hurairah narrated that the Messenger of Allah (s.a.w) said:
"Every child is born upon the Millah, then his parents make him a Jew, a Christian, or a idolater." It was said: "O Messenger of Allah! What about those who die before that?" He said: "Allah knows best what they would have done." (TR)
English reference (TR): Vol. 4, Book 6, Hadith 2138 (TR)
Arabic reference (TR): Book 32, Hadith 2287 (TR)