Sunan Abi Dawud, Book 1, Hadith 272 (USC-MSA) ⓘ
Narrated One of the Wives of the Prophet: Ikrimah reported on the authority of one of the wives of the Prophet saying: When the Prophet wanted to do something (i.e. kissing, embracing) with (his) menstruating wife, he would put a garment on her private part.
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا حَمَّادٌ، عَنْ أَيُّوبَ، عَنْ عِكْرِمَةَ، عَنْ بَعْضِ، أَزْوَاجِ النَّبِيِّ صلى الله عليه وسلم أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ إِذَا أَرَادَ مِنَ الْحَائِضِ شَيْئًا أَلْقَى عَلَى فَرْجِهَا ثَوْبًا .
also referenced under: Hadith 272 (DarusSalam) & Hadith 272 (Hasan)