Sahih Al Bukhari Hadith Number 1356

Narrated Anas: A young Jewish boy used to serve the Prophet (peace be upon him) and he became sick. So the Prophet (peace be upon him) went to visit him. He sat near his head and asked him to embrace Islam. The boy looked at his father, who was sitting there; the latter told him to obey Abul-Qasim and the boy embraced Islam. The Prophet (peace be upon him) came out saying: “Praises be to Allah Who saved the boy from the Hell-fire.”

23  Funerals (Al-Janaa’iz)
Hadith number 1356
Volume no 2
Chapter: 79 (If a boy becomes a Muslim and then dies, should a funeral prayer be offered for him? Should Islam be explained to a boy?)