It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her): I was lying with the Messenger of Allah (peace and blessings be upon him) under a sheet when suddenly my menstruation began. I slipped away from there and put on my menstruation clothes. The Messenger of Allah (peace and blessings be upon him) said to me: "Has your menstruation begun?" I said: Yes. He (peace and blessings be upon him) called me, and I lay down with him (peace and blessings be upon him) under the sheet.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1492