Musnad Ahmad 25:952

Muhammad ibn Maymun al-Za'farani narrated to us, he said: Ja'far narrated to me, from his father, from Yazid ibn Hurmuz, who said: Najdah wrote to Ibn Abbas asking him about five matters. Ibn Abbas said: "People claim that Ibn Abbas corresponds with the Haruriyyah, and were it not that I fear concealing my knowledge, I would not have written to him." Najdah wrote to him: "To proceed: Inform me, did the Messenger of Allah (peace and blessings of Allah be upon him) go on military expeditions with women accompanying him? Did he assign them a share [of the spoils]? Did he kill children? When does the orphanhood of an orphan end? And inform me about the khums (one-fifth), to whom does it belong?" Ibn Abbas wrote to him: "The Messenger of Allah (peace and blessings of Allah be upon him) used to go on military expeditions with women accompanying him, so they would treat the sick, but he would not assign them a share, though he would give them a gift from the spoils." "The Messenger of Allah (peace and blessings of Allah be upon him) did not kill children, and you should not kill children, unless you know what al-Khidr knew about the child he killed, so you kill the disbeliever and leave the believer." "You wrote asking me about the orphanhood of an orphan, when does it end? By my life, a man’s beard may grow while he is still weak in taking care of his own affairs. So, when he takes care of his own affairs in the same righteous manner that people do, then the orphanhood has passed." "As for the khums, we used to believe that it belonged to us, but our people refused that for us."