Hadith: A man divorced his wife three times, then another man married her and divorced her before consummating the marriage with her. Her first husband wanted to remarry her, and the Prophet (may Allah's peace and blessings be upon him) was asked about that. He said: No, not until the second husband tastes of her sweetness what the first one tasted

عن عائشة رضي الله عنها ، قالت: طلَّق رجل امرأَته ثلاثا، فَتَزوَّجها رجل، ثم طلَّقها قَبْل أن يَدْخُل بها، فَأَراد زوجها الأول أن يتزوَّجها، فسُئِل رسول الله صلى الله عليه وسلم عن ذلك، فقال: «لا، حتى يَذُوَق الآخرُ مِنْ عُسَيْلَتِها ما ذَاقَ الأوَّل».
[صحيح] - [متفق عليه]

‘Ā’ishah (may Allah be pleased with her) reported: A man divorced his wife three times, then another man married her and divorced her before consummating the marriage with her. Her first husband wanted to remarry her, and the Prophet (may Allah's peace and blessings be upon him) was asked about that. He said: "No, not until the second husband tastes of her sweetness what the first one tasted."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

The wife of Rifā‘ah al-Qurazi came to the Prophet (may Allah's peace and blessings be upon him) and told him that she was married to Rifā‘ah but that he then divorced her thrice, making the divorce irrevocable. She added that she then got married to ‘Abdur-Rahmān ibn Az-Zabīr, who also divorced her after his failure to have sexual intercourse with her. Her first husband wanted to remarry her, and she asked the Prophet (may Allah's peace and blessings be upon him) about that. The Messenger of Allah (may Allah’s peace and blessings be upon him) forbade this remarriage and told her that the permissibility of her remarriage to Rifā‘ah is conditional on having had sexual intercourse with her last husband.