A slave divorced his wife with two pronouncements of divorce, then both of them were freed. May he marry her again?He answered, "Yes."It was asked, "On whose authority?"He replied, "The Messenger of Allah ﷺ gave this verdict."Abdul-Razzaq said, Ibn Mubarak said to Muamar, "Who is this Hasan? He has indeed shouldered an enormous boulder."
أخبرنا محمد بن رافع قال حدثنا عبد الرزاق قال أنبأنا معمر عن يحيى بن أبي كثير عن عمر بن معتب عن الحسن مولى بني نوفل قال
عن عبد طلق امرأته تطليقتين ثم عتقا أيتزوجها قال نعم قال عمن قال أفتى بذلك رسول الله ﷺ قال عبد الرزاق قال ابن المبارك لمعمر الحسن هذا من هو لقد حمل صخرة عظيمة
[Its chain of transmission is daif] Ibn Majah recorded it in the chapter of Divorce, section "One who divorces a slave woman with two pronouncements of divorce and then buys her," Hadith 2082, from the hadith of Abdul-Razzaq, transmitted through the same chain. See also the preceding hadith, and it is found in Kubra, Hadith 5621.