Abu Dawud Book 6, Hadith Number 2194.
Chapter : Not known.
Narated By Abdullah ibn Abbas : Tawus said: AbusSahba’ said to Ibn Abbas: Do you know that a divorce by three pronouncements was made a single one during the time of the Prophet (PBUH), and of AbuBakr and in the early days of the caliphate of Umar? He replied: Yes.