The man became Muslim and he has (i.e., is married to) two sisters
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَبْدُ السَّلاَمِ بْنُ حَرْبٍ، عَنْ إِسْحَاقَ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي فَرْوَةَ، عَنْ أَبِي وَهْبٍ الْجَيْشَانِيِّ، عَنْ أَبِي خِرَاشٍ الرُّعَيْنِيِّ، عَنِ الدَّيْلَمِيِّ، قَالَ قَدِمْتُ عَلَى رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ وَعِنْدِي أُخْتَانِ تَزَوَّجْتُهُمَا فِي الْجَاهِلِيَّةِ . فَقَالَ " إِذَا رَجَعْتَ فَطَلِّقْ إِحْدَاهُمَا " .
It was narrated that Dailami said: “I came to the Messenger of Allah, and I was married to two sisters whom I had married during the Ignorance period. He said: 'When you go back, divorce one of them.' ”