Sahih Muslim Book 003, Hadith Number 0581.
Chapter : Lying with one in menstruation above the waist wrapper.
Umm Salama reported: While I was lying with the Messenger of Allah (may peace be upon him) in a bed cover I menstruated, so I slipped away and I took up the clothes (which I wore) in menses. Upon this the Messenger of Allah (may peace be upon him) said: Have you menstruated? I said: Yes. He called me and I lay down