Narrated Abdullah ibn Sa'd al-Ansari:

Abdullah asked the Messenger of Allah ﷺ: What is lawful for me to do with my wife when she is menstruating? He replied: What is above the waist-wrapper is lawful for you.

The narrator also mentioned (the lawfulness of) eating with a woman in menstruation, and he transmitted the tradition in full.

حَدَّثَنَا هَارُونُ بْنُ مُحَمَّدِ بْنِ بَكَّارٍ، حَدَّثَنَا مَرْوَانُ، - يَعْنِي ابْنَ مُحَمَّدٍ - حَدَّثَنَا الْهَيْثَمُ بْنُ حُمَيْدٍ، حَدَّثَنَا الْعَلاَءُ بْنُ الْحَارِثِ، عَنْ حَرَامِ بْنِ حَكِيمٍ، عَنْ عَمِّهِ، أَنَّهُ سَأَلَ رَسُولَ اللَّهِ ﷺ مَا يَحِلُّ لِي مِنَ امْرَأَتِي وَهِيَ حَائِضٌ قَالَ " لَكَ مَا فَوْقَ الإِزَارِ " . وَذَكَرَ مُؤَاكَلَةَ الْحَائِضِ أَيْضًا وَسَاقَ الْحَدِيثَ .