Musnad Ahmad 25:826

'Abd al-Wahhab ibn 'Ata narrated to us, Jarir ibn Hazim informed us, from Qays ibn Sa'd, from Yazid ibn Hurmuz, that Najdah wrote to Ibn 'Abbas asking him about the share of the near relatives (Dhu al-Qurba), to whom does it belong? And about the orphan, when does his orphanhood end? And about the woman and the slave, do they witness the spoils of war? And about killing the children of the polytheists? Ibn 'Abbas said: "Were it not that I might deter him from something he is falling into, I would not have answered him." And he wrote to him: "You wrote to me asking about the share of the near relatives, to whom does it belong? We used to consider it to be for the relatives of the Messenger of Allah (peace be upon him), but our people refused that for us." "And about the orphan, when does his orphanhood end? He said: When he reaches puberty and good is perceived from him." "And about the woman and the slave, do they witness the spoils of war? They have no share, but they are given a gift and given something." "And about killing the children of the polytheists? The Messenger of Allah (peace be upon him) did not kill them, so do not kill them, unless you know about them what Al-Khidr knew about the boy when he killed him."