Musannaf Ibn Abi Shayba 3:3836

Abu Bakr narrated to us, he said: Isa ibn Yunus narrated to us, from Amr, from al-Hasan, who attributed it (marfu'an) to the Prophet, he said: "When the young girl reaches the age of menstruation, no prayer is accepted from her except with a head covering (khimar)."