Musnad Ahmad 2375

It was narrated that Ibn 'Abbas (رضي الله عنه) said: Rukanah bin 'Abd Yazeed, a man of Banul-Muttalib, divorced his wife thrice in one sitting, then he missed her sorely. The Messenger of Allah (ﷺ) asked him: “How did you divorce her?" He said: I divorced her thrice. He said: “In one sitting?" He said: Yes. He said: “That is only one divorce (talaq); take her back if you want." So he took her back, Ibn 'Abbas thought that talaq is only to be done just after the woman becomes pure from menses.