(Killing Enemies' Children is Forbidden)
Al-Aswad ibn Sari' (ra) reported that, on the day of Hunain battle, the Prophet (PBUH) dispatched a group of soldiers who fought against the disbelievers and, consequently, killed some of their children. Upon their return, the Prophet asked, "Why did you kill the children?" They replied, "O messenger of Allah, they are children of polytheists. The Prophet thereupon said, "The best of you today are children of idolaters. Do not kill the children! [repeating it twice]."