'O Messenger of Allah! I irrevocably divorced my wife.' So he said: 'What did you intend by that?' I said: 'One (divorce).' He said: '(Do you swear) By Allah?' I said: 'By Allah.' He said: 'Then it is as you intended.'"
Jami` at-Tirmidhi Book 13, Hadith 3
← Previous Hadith His father divorced his wife during her menses, so Umar asked the Prophet about that and he said: "Tell him to take her back, then let him divorce her while she is pure or pregnant."

Jami` at-Tirmidhi Book 13, Hadith 2 Next Hadith → "I said to Abu Ayyub: 'Do you know of anyone who said that: "Your case is up to you?" counts as three besides Al-Hasan?' He said: "No, not besides Al-Hasan.' Then he said: 'O Allah forgive me - except for what has been narrated to me by Qatadah, from Kathir the freed slave of Banu Samurah, from Abu Salamah, from Abu Hurairah, that the Prophet said: "Three.'"Abu Ayyub said: 'So I met Kathir the freed slave of Banu Samurah and asked him about it, but he was not aware of it. So I returned to Qatadah and informed him about that and he said: "He forgot."

Jami` at-Tirmidhi Book 13, Hadith 4