Sahih al-Bukhari 6599
Narrated Abu Huraira:
Allah's Apostle was asked about the offspring of the pagans. He said, "Allah knows what they would have done (were they to live)." Narrated Abu Huraira: Allah's Apostle ﷺ said, "No child is born but has the Islamic Faith, but its parents turn it into a Jew or a Christian. It is as you help the animals give birth. Do you find among their offspring a mutilated one before you mutilate them yourself?" The people said, "O Allah's Apostle! What do you think about those (of them) who die young?" The Prophet ﷺ said, "Allah knows what they would have done (were they to live)."
حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، عَنْ يُونُسَ، عَنِ ابْنِ شِهَابٍ، قَالَ وَأَخْبَرَنِي عَطَاءُ بْنُ يَزِيدَ، أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ، يَقُولُ سُئِلَ رَسُولُ اللَّهِ ﷺ عَنْ ذَرَارِيِّ الْمُشْرِكِينَ فَقَالَ {اللَّهُ أَعْلَمُ بِمَا كَانُوا عَامِلِينَ }