Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: In the time of the Messenger of Allah (peace and blessings be upon him), of Sayyiduna Abu Bakr (may Allah be pleased with him), and for the first two years of the caliphate of Sayyiduna Umar (may Allah be pleased with him), three divorces were counted as only one. Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) said: "People have become hasty in a matter in which they had latitude; what if we were to enforce all three divorces?" So Sayyiduna Umar (may Allah be pleased with him) enforced all three.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14972