Bukhari

Hadith Commentary:
Hazrat Umar radi Allahu anhu immediately acknowledged his forgetfulness and bowed his head before the Prophetic hadith.
This is precisely the characteristic of a believing Muslim: that he should abandon all other considerations and submit himself before the noble hadith.
The correspondence between the chapter and the hadith is evident, as some ahadith became known to Hazrat Umar radi Allahu anhu at a later time; this is not a matter of fault.
The content of the hadith encompasses a very significant literary, ethical, and social matter. May Allah grant every Muslim the ability to act upon it. Ameen.

Hadith Commentary:
1.
Hazrat Umar radi Allahu anhu was a very eminent Companion.
Despite this, the ruling of isti’dhan (seeking permission) remained hidden from him, until he came to know of this matter through Hazrat Abu Musa Ash’ari radi Allahu anhu.
When he found out, he immediately accepted it.
This is not a flaw in any way.
2.
Every believer should have this very quality: that upon learning a hadith of the Messenger of Allah sallallahu alayhi wa sallam, he should submit to it wholeheartedly. This matter is clarified through the following examples:
➊
Hazrat Abu Bakr Siddiq radi Allahu anhu did not know about the inheritance of the grandmother (paternal or maternal).
Hazrat Mughirah bin Shu’bah radi Allahu anhu informed him.
➋
Hazrat Umar Farooq radi Allahu anhu did not know whether a wife receives a share from her husband’s blood money (diyah) or not, so Hazrat Dahiak bin Sufyan radi Allahu anhu informed him with reference to a hadith.
➌
Hazrat Uthman radi Allahu anhu did not know where a wife should spend her waiting period (‘iddah) after her husband’s death. Hazrat Abu Sa’id Khudri radi Allahu anhu informed him and cited a hadith.
➍
Hazrat Ali radi Allahu anhu’s legal opinion (fatwa) was that if a woman’s husband dies and she is pregnant, she must observe whichever waiting period (‘iddah) is longer. He was informed of the correct ruling by Sabi’ah bint Harith radi Allahu anha, who narrated her own incident.
➎
Hazrat Abu Hurairah radi Allahu anhu did not consider it permissible for a person in a state of major ritual impurity (junub) to fast. Hazrat Umm Salamah radi Allahu anha and Hazrat A’ishah radi Allahu anha informed him of their own practice, which compelled him to retract his position.
3.
Hazrat Umar radi Allahu anhu had a practice that he and his Ansari neighbor had agreed to take turns attending the gatherings of the Messenger of Allah sallallahu alayhi wa sallam; the one who attended would inform the other of the religious matters discussed.
(Sahih al-Bukhari, Kitab al-‘Ilm, Hadith: 89)
Despite this, there were some ahadith that he did not come to know of, for example:
b.
Regarding wiping (masah) over leather socks (khuffayn), he was informed by Hazrat Sa’d bin Abi Waqqas radi Allahu anhu.
c.
All the fingers of the hand are equal in terms of blood money (diyah); no distinction is made between large and small. He learned this from Amr bin Hazm radi Allahu anhu.
In this way, there are numerous issues about which Hazrat Umar radi Allahu anhu did not have knowledge.
(Fath al-Bari: 13/393)
Note:
Hazrat Umar radi Allahu anhu requested testimony from Hazrat Abu Musa Ash’ari radi Allahu anhu for the authenticity and corroboration of the hadith.
This does not mean that he did not accept a solitary report (khabar wahid), because even after the testimony of one person, it still remains a solitary report and does not reach the level of mass transmission (tawatur).
Wallahu al-musta’an.