"The Messenger of Allah was asked about the children of the idolators and he said: 'Allah knows best what they would have done."' (Using translation from Nasāʾī 1949)
سُئِلَ رَسُولُ اللهِ ﷺ عَنْ أَطْفَالِ الْمُشْرِكِينَ فَقَالَ اللهُ أَعْلَمُ بِمَا كَانُوا عَامِلِينَ