Sunan an-Nasa'i — The Book of Purification — Hadith No: 281
Translation
It was narrated from Al-Miqdam bin Shuraih that his father said:"I heard 'Aishah say: 'The Messenger of Allah (ﷺ) would hand me the vessel and I would drink from it, while I was menstruating, then I would give it to him and he would look for the place where I had put my mouth and put that to his mouth