An Nasai: Hadith 3422

"I said to Ayyub: 'Do you know anyone who said concerning the phrase 'It is up to you' that it is equivalent to three (divorces) except Al-Hasan?' He said: 'No.' Then he said: 'O Allah! Grant forgiveness, sorry.'" Qatadah narrated to me from Kathir the freed slave of Ibn Samurah, from Abu Salamah, from Abu Hurairah, that the Prophet said: "Three." I met Kathir and asked him, and he did not know of it. I went back to Qatadah and told him, and he said: "He forgot."