Chapter 27: The Book of Divorce
It was narrated from Ibn Tawus, from his father, that Abu As-Sahba' came to Ibn 'Abbas and said: "O Ibn 'Abbas! Did you not know that the threefold divorce during the time of the Messenger of Allah and Abu Bakr, and during the early part of 'Umar' s Caliphate, used to be counted as one divorce?" He said: "Yes."
Sunan an-Nasa'i 3406