Sayyiduna al-Aswad bin Sari' (may Allah be pleased with him), who was a poet and the first to preach and tell stories in this mosque, narrates: The killing in battle went so far that they killed even the children. This reached the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Are not the best of you from the children of the polytheists? No child is born except upon the fitrah (natural disposition) of Islam, until he begins to speak clearly; then his parents make him a Jew, or a Christian, or a Magian."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 823