Abu al-Sahba' said to Ibn Abbas (may Allah be pleased with them both): "Do you know that during the time of the Messenger of Allah (peace and blessings be upon him) and of Abu Bakr (may Allah be pleased with him), and in the first three years of the caliphate of Umar (may Allah be pleased with him), three pronouncements of divorce were counted as one?" Ibn Abbas (may Allah be pleased with them both) said: "Yes."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10871