In the divorce issue, why has the ruling of the second Caliph, Umar (Radiya Allahu Anhu) been overruled by later scholars. Does it imply that Umar lacks the sound knowledge of Qur’an and Sunnah or he couldn’t interpret it well?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The scholars who have stated that the issuing of three divorces at a time is not considered as a Bain (irrevocable) divorce (giving three divorces after which a husband is not allowed to take his wife back to conjugal life unless the wife marries another man and has sex with him before getting divorced from him), which is an opinion that is different from the opinion of Umar (Radiya Allahu Anhu) they based it on religious evidences.

They did not differ with him just for a desire, but they saw that Umar made effective the three divorces given at the same time as Talaq Bain (irrevocable one) with the object of reprimanding people, when he saw that men used this expression a lot and played with it.  The evidence of the above scholars is what is reported by Muslim that Abu Assahba said to Ibn Abbas: "Tell us from your knowledge.  Was the wording ‘divorced 3 times at a time’ considered at the time of the Prophet (Sallallahu Alaihi wa Sallam) and at the time of Abu Bakr (Radiya Allahu Anhu) as divorced once?  He replied: ‘This was the case, but when the people got used to saying that, then Umar considered it to be an irrevocable divorce".

The majority of scholars responded to this Hadith and other similar Ahadith, and relied on other evidences.

Anyway, each group relied on evidences that support their opinion.  All of them will be rewarded.  Those who are correct in their Fatwa will be rewarded twice, and those who are wrong will get one reward for their Ijtihad.

Last, we thank the questioner for his respect to the scholars.  This is a praiseworthy quality in a person.

Allah knows best.