Abu Dawud Book 1, Hadith Number 213.

Chapter : On mutual contract and eating with a menstruating woman.

Narated By Mu’adh ibn Jabal : I asked the Apostle of Allah (PBUH): What is lawful for a man to do with his wife when she is menstruating? He replied: What is above the waist-wrapper, but it is better to abstain from it, too.

Abu Dawud said: This tradition is not strong.