Suwayd bin Ghafalah (may Allah have mercy on him) said: Aishah al-Khath'amiyyah (may Allah be pleased with her) was married to al-Hasan bin Ali (may Allah be pleased with them both). When Ali (may Allah be pleased with him) was martyred, she said to al-Hasan bin Ali (may Allah be pleased with them both): Congratulations to you on the caliphate. Al-Hasan (may Allah be pleased with him) said: "You show joy at the killing of Ali (may Allah be pleased with him)! Go, you are divorced three times." She wrapped herself in her garments and sat until she completed her waiting period ('iddah). Then al-Hasan (may Allah be pleased with him) sent her the remainder of her dowry (mahr) and an additional ten thousand. When the messenger came, Aishah (may Allah be pleased with her) said: This is little wealth compared to a beloved who is parting. When Aishah's (may Allah be pleased with her) words reached al-Hasan (may Allah be pleased with him), he wept and then said: Had I not heard from my maternal grandfather, or had my father not told me, that he (peace and blessings be upon him) said: "Whoever divorces his wife three times at the time of the menstrual periods, or three times in an unspecified manner, she is not lawful for him until she marries another husband," I would certainly have taken her back.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14971