اَللَّاوِيِّينَ 18:18

وَلَا تَأْخُذِ ٱمْرَأَةً عَلَى أُخْتِهَا لِلضِّرِّ لِتَكْشِفَ عَوْرَتَهَا مَعَهَا فِي حَيَاتِهَا.

Neither shalt thou take a wife to her sister, to vex her, to uncover her nakedness, beside the other in her life time.