Musnad Ahmad 1153:1998

Yazid narrated to us, he said: Hisham informed us, from Muhammad, that Aisha stayed with Umm Talha al-Talhat and saw her daughters praying without head coverings (khumur). She said: "I see that your daughters have reached puberty, or some of them have." She said: "Yes." Aisha said: "No girl among them who has reached puberty should pray unless she is wearing a head covering (khimar). For the Messenger of Allah (peace and blessings of Allah be upon him) entered upon me while I had a young girl with me, and he threw his lower garment (hizār) to me and said: 'Divide it between this one and the girl who is with Umm Salama, for I do not see them except that they have reached puberty,' or 'I do not see her except that she has reached puberty.'"