Allaamah Ibn Hajar Al-Asqalani and the question of three Talaaq in one go / at once

'According to the prevailing opinion, all the 3 Talaaq will be binding due to the consensus (Ijma) that took place at the time of Hazrat Umar (Radiyallahu Anhu). There is no one [whose name] can be mentioned, who opposed that at the time of Hazrat Umar (Radiyallahu Anhu). Thus, their consensus on that indicates the existence of an element that has abrogated the previous law although this remained unknown by some initially, until this became public for everyone during the time of Hazrat Umar (Radiyallahu Anhu). The one, who opposes that after the consensus that took place, is effectively rejecting Ijma. According to the opinion of the majority, there is no consideration for a person who creates divergence [regarding certain subject] after unanimity." 

(Fath-ul-Bari of Ibn Hajar (Rahmatullahi alayh), the commentary on Saheeh Bukhari by Allaamah Ibn Hajar)

[English version of "Allaamah Ibn Hajar Al-Asqalaani et la question de trois talaaq ene seul coup" – Al Jamiat – Vol.3 No.11]