Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) was asked about the children of the polytheists, and he (peace and blessings be upon him) said: "Allah knows best what they would have done, when He created them."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12395