Musnad Ahmad 1153:475

Yahya ibn Ishaq narrated to us, he said: Abu 'Awanah informed us, from 'Umar ibn Abi Salamah, from his father, from 'Aishah, she said: "I used to sleep with the Messenger of Allah, may Allah bless him and grant him peace, on a mattress while I was menstruating and wearing a garment."