Muslim sexual modesty

It was Hadith attributed to the Prophet himself (may Allah have mercy upon him) that a man and women should never see each other entirely naked, even if they were formally paired. So in the twelfth and thirteenth centuries (and perhaps earlier) those members of the upper classes who were concerned with such proprieties adopted practice of wearing a sheer muslin shirt called a ghilala while engaged in intimate pastimes. This fulfilled the letter of Hadith while concealing nothing and offering no impediment to the activity. Both of a couple would wear such a ghilala.