Musannaf Ibn Abi Shaybah

Hazrat Abu Bakr (may Allah have mercy on him) says that Hazrat Umar bin Abdul Aziz (may Allah have mercy on him) asked me about irrevocable divorce, that what do people say about it. I told him that Aban bin Uthman (may Allah have mercy on him) used to say that it will be counted as one divorce. Hazrat Umar (may Allah have mercy on him) said that even if there are a thousand divorces, after giving an irrevocable divorce, not a single divorce will remain. Whoever used the word "irrevocable" has reached the limit.