Musannaf Ibn Abi Shayba 3:3846

Yahya ibn Adam narrated to us, from Hammad ibn Salamah, from Qatadah, from Ibn Sirin, from Safiyyah, from Aisha, that the Prophet (peace and blessings of Allah be upon him) said: "Allah does not accept the prayer of a menstruating woman (a woman who has reached the age of puberty) except with a head covering (khimar)."