Prohibited to you ( For marriage ) are : - Your mothers , daughters , sisters ; father 's sisters , Mother 's sisters ; brother 's daughters , sister 's daughters ; foster-mothers ( Who gave you suck ) , foster-sisters ; your wives ' mothers ; your step-daughters under your guardianship , born of your wives to whom ye have gone in , - no prohibition if ye have not gone in ; - ( Those who have been ) wives of your sons proceeding from your loins ; and two sisters in wedlock at one and the same time , except for what is past ; for Allah is Oft-forgiving , Most Merciful ; -