Muslim, Book 004, Number 1039:

Al-Aswad reported that 'A'isha said: You have made us equal to the dogs and the asses, whereas I lay on the bedstead and the Messenger of Allah (may peace be upon him) came there and stood in the middle of the bedstead and said prayer. I did not like to take off the quilt from me (in that state), so I moved away quietly from the front legs of the bedstead and thus came out of the quilt.

http://www.usc.edu/schools/college/crcc ... 4.smt.html