Bukhari

Hadith Commentary:
The magnificent sermon of Abu Bakr (radi Allahu anhu) saved the unity of the Ummah from being scattered.
The proposal put forth by the Ansar to appoint two leaders was not correct,
because two swords cannot be kept in one sheath.
In the narration, the curse (bad-dua) of Umar (radi Allahu anhu) for Sa’d bin Ubadah (radi Allahu anhu) is mentioned.
He was the one who brought the proposal to appoint two leaders.
God forbid, if this had been acted upon, the result would have been extremely dire.
It is said that after this, Ubadah went to the land of Sham (Greater Syria) and passed away there.
From this hadith, the obligation (wujub) of appointing a caliph (khalifah) is established, because the noble Companions (Sahabah kiram) gave it precedence even over the preparation and burial (tajhiz wa takfin) of the Prophet (sallallahu alayhi wa sallam).
Alas, the Ummah soon forgot this obligation.
The first corruption that arose was that kingship (mulukiyyah) took the place of the caliphate (khilafah).
Then, when Muslims entered the ranks of the world, they encountered various nations, and being influenced by them, they forgot this communal obligation and became victims of disunity.
Today is a different era altogether; although even now there are many Muslim governments established in the world, most are deprived of the reflection of the rightly guided caliphate (khilafah rashidah).
May Allah, the Most Pure, grant the Muslims mutual harmony in this era full of tribulations, so that they may unite and collectively serve the Islamic Ummah.
Ameen.

Hadith Commentary:
➊
This hadith establishes the virtue of Abu Bakr al-Siddiq radi Allahu anhu, in that his insight, magnificent address, and timely action saved the unity of the Ummah from being scattered.
It is also understood from this that his knowledge surpassed that of Umar radi Allahu anhu and indeed all the other Companions.

➋
The proposal put forward by the Ansar—that two leaders (amirs) should be appointed—was not correct.
Had this been acted upon, it would have resulted in dreadful consequences against the unity of the Ummah.
Umar radi Allahu anhu responded to this movement promptly and spontaneously, saying:
"Two swords cannot fit in one sheath."
And he took the hand of Abu Bakr radi Allahu anhu and said:
"Tell me, in (the verse) ﴿إِذْ هُمَا فِي الْغَارِ﴾, who were the two in the cave? In ﴿ذْ يَقُولُ لِصَاحِبِهِ﴾, who was with the Messenger of Allah sallallahu alayhi wa sallam? And in ﴿إِنَّ اللَّهَ مَعَنَا﴾, to whom was the company of Allah granted?"
Then he extended his hand and pledged allegiance (bay‘ah) to Abu Bakr radi Allahu anhu and said to the people:
"You also pledge allegiance to him."
Thus, all the people pledged allegiance to Abu Bakr radi Allahu anhu.
(Fath al-Bari: 7/41)

➌
This hadith also indicates the importance of the office of the Caliphate (khilafah), as the noble Companions radi Allahu anhum gave it precedence over the preparation and burial (tajhiz wa takfin) of the Messenger of Allah sallallahu alayhi wa sallam.
It is regrettable that today Muslims have forgotten this important obligation.
Although there are numerous Muslim governments established in the world today, most are deprived of even a glimpse of the rightly guided Caliphate (khilafah rashidah).
And Allah is the One whose help is sought.