A man divorced his wife and she married another man who proved to be impotent and divorced her. She could not get her satisfaction from him, and after a while he divorced her. Then she came to the Prophet and said, "O Messenger of Allah ﷺ! My first husband divorced me and then I married another man who entered upon me to consummate his marriage but he proved to be impotent and did not approach me except once during which he benefited nothing from me. Can I remarry my first husband in this case?" Messenger of Allah ﷺ said, "It is unlawful to marry your first husband till the other husband consummates his marriage with you." (Using translation from Bukhārī 5265)
طَلَّقَ رَجُلٌ امْرَأَتَهُ فَتَزَوَّجَتْ زَوْجًا غَيْرَهُ وَدَخَلَ بِهَا وَمَعَهُ مِثْلُ الْهُدْبَةِ فَلَمْ يَصِلْ مِنْهَا إِلَى شَيْءٍ تُرِيدُهُ فَلَمْ يَلْبَثْ أَنْ طَلَّقَهَا فَأَتَتِ النَّبِيَّ ﷺ فَسَأَلَتْهُ عَنْ ذَلِكَ فَقَالَتْ يَا رَسُولَ اللهِ إِنَّ زَوْجِي طَلَّقَنِي وَإِنِّي تَزَوَّجْتُ زَوْجًا غَيْرَهُ فَدَخَلَ بِي وَلَمْ يَكُنْ مَعَهُ إِلَّا مِثْلُ الْهُدْبَةِ فَلَمْ يَقَرَبْنِي إِلَّا هَنَةً وَاحِدَةً لَمْ يَصِلْ مِنِّي إِلَى شَيْءٍ أَفَأَحِلُّ لِزَوْجِيَ الْأَوَّلِ؟ فَقَالَ لَا تَحِلِّينَ لِزَوْجِكِ الْأَوَّلِ حَتَّى يَذُوقَ الْآخَرُ عُسَيْلَتَكِ وَتَذُوقِينَ عُسَيْلَتَهُ