Bukhari

Hadith Commentary:
The complete hadith will be mentioned ahead in the chapter of Faith and Vows (Bab al-Iman wa al-Nudhur).
From this, the great kindness and affection of the Prophet (sallallahu alayhi wa sallam) towards Umar (radi Allahu anhu) becomes evident.

Hadith Commentary:
➊
From this hadith, we learn of the great love and special favor that the Messenger of Allah (sallallahu alayhi wa sallam) had for Umar (radi Allahu anhu), because the Messenger of Allah (sallallahu alayhi wa sallam) holding his hand is a sign of perfect love.

➋
Imam Bukhari (rahimahullah) has narrated this hadith here in a very concise manner. The complete hadith is as follows: Once Umar (radi Allahu anhu) said:
"O Messenger of Allah (sallallahu alayhi wa sallam)! You are more beloved to me than everything except my own self."
The Messenger of Allah (sallallahu alayhi wa sallam) said:
"By Him in Whose hand is my soul! Faith will only be complete when you consider me more beloved than your own self."
Umar (radi Allahu anhu) immediately said:
"O Messenger of Allah (sallallahu alayhi wa sallam)! You are more dear to me than my own self."
He (sallallahu alayhi wa sallam) said:
"O Umar (radi Allahu anhu)! Now faith has reached its perfection."
(Sahih al-Bukhari, al-Iman wa al-Nudhur, Hadith: 6632)

➌
The incident of the martyrdom of Umar (radi Allahu anhu) is extremely heart-rending.
Its details will be mentioned later.
Abu Lu’lu’ah the Magian, the slave of Mughirah ibn Shu’bah, struck him three times with a poisoned dagger.
Due to this, he could not survive and passed away after several days of being wounded.
Sayyiduna Suhayb (radi Allahu anhu) led his funeral prayer.
He is buried in the chamber of Sayyidah Aisha (radi Allahu anha) alongside the Messenger of Allah (sallallahu alayhi wa sallam) and Abu Bakr (radi Allahu anhu).
His death occurred on 26th Dhu al-Hijjah, 23 AH, corresponding to 6th October 644 CE.
Radi Allahu anhu.

Hadith Commentary:
(1)
Imam Bukhari rahimahullah has mentioned this hadith in detail at another place.
(Sahih al-Bukhari, Al-Ayman wa al-Nudhur, Hadith: 6632)
The scholars of language have defined musafahah (handshaking) in these words:
Musafahah is from the form "mufa‘alah."
By it is meant joining the inner part of the palm with the inner part of another's palm.
(Al-Nihayah: 3/43)
This is also evident from the hadith presented by Imam Bukhari rahimahullah, because when the hand is grasped, the palm of one hand meets the palm of the other.
(Fath al-Bari: 11/67)
(2)
The act of the Messenger of Allah sallallahu alayhi wa sallam holding the hand of Umar radi Allahu anhu is itself a form of musafahah (handshaking), which is why Imam Bukhari rahimahullah has mentioned this hadith under the chapter heading of musafahah. Accordingly, there is further clarification of this in another hadith.
It is narrated from Anas radi Allahu anhu that the Messenger of Allah sallallahu alayhi wa sallam said:
“When two Muslims meet each other and one of them takes the hand of his companion, it is a right upon Allah that He pays attention to their supplications and forgives them before their hands separate.”
(Musnad Ahmad: 3/142)