I asked the Messenger of Allah ﷺ about what is permissible for a man with his wife while she is menstruating. He said, "Whatever is above the waist-wrapper, though abstaining from that is better."
حدثنا هشام بن عبد الملك اليزني حدثنا بقية بن الوليد عن سعد الأغطش وهو ابن عبد الله عن عبد الرحمن بن عائذ الأزدي قال هشام وهو ابن قرط أمير حمص
سألت رسول الله ﷺ عما يحل للرجل من امرأته وهي حائض قال فقال ما فوق الإزار والتعفف عن ذلك أفضل
[Its chain of transmission is daif] Tabarani reported it in Al-Kabir, 20/100, no. 194, through another route from Abdul-Rahman bin Aaidh, and he did not meet Muaz bin Jabal, as stated in Jami Tahsil by Alai, p. 223.