Musnad Ahmad 1153:1668

Waki’ narrated to us, he said: Talhah ibn Yahya narrated to us, from ‘Ubaydullah ibn ‘Abdullah ibn ‘Utbah—he heard it from him—from ‘Aishah, she said: The Messenger of Allah (peace and blessings of Allah be upon him) used to pray at night while I was at his side, and I was menstruating, and I had a garment (mirt) on me, and part of it was on him.