Sunan Abu Dawud
272
Sahih+3

Narrated One of the Wives of the Prophet: Ikrimah reported on the authority of one of the wives of the Prophet (ﷺ) saying: When the Prophet (ﷺ) wanted to do something (i.e. kissing, embracing) with (his) menstruating wife, he would put a garment on her private part

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid