Musnad Ahmad 1153:1732

Waki’ narrated to us, Sufyan narrated to us, from Mansur, from Ibrahim, from al-Aswad, from ‘Aishah, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to command me to wear an izar (waist-wrapper) while I was menstruating, then he would engage in physical intimacy with me."