Yahya related to me from Malik from Zayd ibn Aslam that a manquestioned the Messenger of Allah, may Allah bless him and grant himpeace, saying, "What is permitted me from my wife when she ismenstruating?" The Messenger of Allah, may Allah bless him and granthim peace, said, "Let her wrap her waist-wrapper round herselftightly, and then what is above that is your concern."
USC-MSA web (English) reference: Book 2, Hadith 95
Arabic reference: Book 2, Hadith 125