Sahih Al Bukhari Hadith Number 1384

Narrated Abu Huraira: The Prophet (peace be upon him) was asked about the offspring of pagans (Mushrikeen); so he said, “Allah knows what sort of deeds they would have done.”

23  Funerals (Al-Janaa’iz)
Hadith number 1384
Volume no 2
Chapter: 92 (The (dead) children of Al-Mushrikun)