The Messenger of Allah ﷺ was asked about the children of the polytheists, and he replied, "Allah knows best what they would have done."
أخبرنا إسحق قال أنبأنا سفيان عن الزهري عن عطاء بن يزيد الليثي
سئل رسول الله ﷺ عن أولاد المشركين فقال الله أعلم بما كانوا عاملين
Bukhari narrated it in the Book of Funerals, chapter "What was said about the children of the polytheists," hadith no. 1384, and Muslim narrated it in the Book of Divine Decree, chapter "The meaning of 'Every child is born upon fitrah'" etc., hadith no. 2659, both from the hadith of Zuhri by this route, and it is in Al-Kubra, hadith no. 2076.Ishaq is Ibn Ibrahim bin Makhlad, and Sufyan is Ibn Uyayna.