Sahih Muslim 294
Sahih Muslim · Book 3: The Book of Menstruation · Touching a menstruating woman above the izar (waist wrapper)
Maimuna (the wife of the Holy Prophet) reported:
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى ، أَخْبَرَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ ، عَنِ الشَّيْبَانِيِّ ، عَنْ عَبْدِ اللَّهِ بْنِ شَدَّادٍ ، عَنْ مَيْمُونَةَ ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُبَاشِرُ نِسَاءَهُ فَوْقَ الإِزَارِ وَهُنَّ حُيَّضٌ .
The Messenger of Allah (ﷺ) contacted and embraced his wives over the waist-wrapper when they were menstruating.