Once, Abu Bakr appeared in the masjid, walking swiftly, having raised his lower garment so that his shin was visible. Upon seeing him, the Prophet (salla Allahu alayhi wa sallam) said, 'It appears your companion [meaning Abu Bakr] has been in an argument!'

When he came to the gathering, he greeted the Prophet (SAW) and said, 'O Messenger of Allah! There was an issue between Umar b. al-Khattab and me, and I got angry [and said some things], but then regretted it. So I asked him to forgive me, but he refused! That is why I came to you.'

The Prophet (SAW) said, 'Allah will forgive you, O Abu Bakr' and repeated it three times. 

In the meantime, Umar regretted what had transpired, and went to the house of Abu Bakr, hoping to find him there, but he was not there. So Umar made his way to the masjid, and saw him there. When Umar greeting the Prophet (SAW), the anger from the Prophet's (SAW) face was obvious. After a while, Abu Bakr himself felt pity for Umar, so he half-stood up on his knees and said, 'O Messenger of Allah! By Allah I did more wrong than he did [to me].' 

The Prophet (SAW) replied, "Allah sent me to you: while all of you said, 'He lies!', Abu Bakr said, 'He has spoken the truth!' And it is Abu Bakr who has shared with me himself and his wealth [like no other], so will you not leave my Companion (sahibi) alone?!" 

So no one ever interfered with Abu Bakr after that. [Reported by al-Bukhari]. 

There are so many benefits from this beautiful narration:
1) The Companions are humans, and so trivial differences do indeed occur between them
2) The gentleness of Abu Bakr, by realizing that perhaps he had used harsh words, and by asking Umar to forgive him, and by then excusing him in the end. 
3) The soft side of Umar as well, having realized that he should have forgiven Abu Bakr and therefore walking to his house to apologize.
4) The high status of Abu Bakr and the unconditional praise that the Prophet (salla Allahu alayhi wa sallam) gave him. 
5) By explicit testimony of the Quran and of the Sunnah, Abu Bakr is a Companion (sahabi); whoever disputes this has negated the Quran and Sunnah.

6) it is not only the companions (r.a.) who defended the Prophet (saws), but vice versa 

7) The narrator did not mention the topic or reason of the disagreement between Abu Bakr and Umar showing us that it's better not to focus or dwell on divisive issues

8) The Companions' empathizing for one another and putting themselves in the others' shoes

9) Rushing to take the blame on oneself rather than seeing his brother bear the brunt of the Prophet's anger. A true case of love for your brother what you love for yourself!