وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عُبَيْدَ اللَّهِ بْنَ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَرْسَلَ إِلَى عَائِشَةَ يَسْأَلُهَا هَلْ يُبَاشِرُ الرَّجُلُ امْرَأَتَهُ وَهِيَ حَائِضٌ فَقَالَتْ لِتَشُدَّ إِزَارَهَا عَلَى أَسْفَلِهَا ثُمَّ يُبَاشِرُهَا إِنْ شَاءَ ‏.‏

Yahya related to me from Malik from Nafi that Ubaydullah ibnAbdullah ibn Umar sent a question to A'isha asking her, "May a manfondle his wife when she is menstruating?" She replied, "Let her wrapher waist-wrapper around her lower part and then he may fondle her ifhe wishes." Translation Not Available

Book Ref: Muwatta Imam Malik Book 2 Hadith 127
Web Ref:  Muwatta Imam Malik Book 2 Hadith 97