22وَلا تَنكِحوا ما نَكَحَ آباؤُكُم مِنَ النِّساءِ إِلّا ما قَد سَلَفَ ۚ إِنَّهُ كانَ فاحِشَةً وَمَقتًا وَساءَ سَبيلًا(Saheeh International)And do not marry those [women] whom your fathers married, except what has already occurred.1 Indeed, it was an immorality and hateful [to Allāh] and was evil as a way. Before Islām. After the ruling was revealed by Allāh, men were required to release those women unlawful to them (e.g., a stepmother, one of two sisters, or any wives over the limit of four). The same obligation applies to one once he has accepted Islām.