Ibn Majah

Commentary: (1) The word (Khalil) is derived from (khullah). This is the highest degree of love in which partnership is not possible. Love of a lesser degree can be shared with more than one person, which is why the Prophet sallallahu alayhi wa sallam used the word "love" for others as well, but the term "khullah" was not applied to anyone else—not even to the most virtuous and the closest Companion of the Prophet sallallahu alayhi wa sallam, Abu Bakr radi Allahu anhu, who did not attain this rank. From Allah, this station was granted to Prophet Ibrahim alayhis salam, and after him, to Muhammad sallallahu alayhi wa sallam. The Prophetic statement is:
(“Indeed, Allah the Exalted has taken me as a Khalil, just as He took Ibrahim as a Khalil.”) (Sahih Muslim, al-Masajid, Chapter: The prohibition of building mosques over graves...etc., Hadith: 532)
“Allah the Exalted has made me a Khalil just as He made Ibrahim alayhis salam a Khalil.”

(2)
From this hadith, the virtue of Abu Bakr as-Siddiq radi Allahu anhu is evident, as the Messenger of Allah sallallahu alayhi wa sallam considered him worthy of the highest degree of love.

Explanation:
1:
(Khullah) is a special state of friendship, the meaning of which is that the love of a friend permeates the heart completely.
This is a state higher and more exalted than "love."
That is why the Prophet (sallallahu alayhi wa sallam) or Ibrahim (alayhis salam) gave this status only to Allah Ta'ala.
As for love, the Prophet (sallallahu alayhi wa sallam) had love for all the Companions, the truthful, and the righteous.
And among the Companions, Abu Bakr as-Siddiq (radi Allahu anhu) holds the most superior rank.
So much so that, if it were possible, the Prophet (sallallahu alayhi wa sallam) would have made Abu Bakr his "Khalil" (intimate friend).
This indicates a very great virtue of Abu Bakr (radi Allahu anhu).

Benefit:
From this hadith, the tremendous virtue of Sayyiduna Abu Bakr as-Siddiq radi Allahu anhu is established. The meaning of "khaleel" is: intimate friend, well-wisher, sympathizer. (al-Qamus al-Waheed: 471) The commentator of the Qur’an, Hafiz Salahuddin Yusuf rahimahullah, states: The meaning of "khaleel" is one in whose heart the love of Allah Ta’ala becomes so firmly rooted that there remains no place for anyone else. "Khaleel" is on the pattern of "fa‘eel" with the meaning of "faa‘il" (active participle), just as "‘aleem" means "‘aalim" (knower), and some say it is with the meaning of "maf‘ool" (passive participle), just as "habeeb" means "mahboob" (beloved). Sayyiduna Ibrahim alayhis salam was certainly both a lover of Allah Ta’ala and beloved to Him. (Fath al-Qadeer) (Tafsir Ahsan al-Bayan: 267) The highest degree of love is called "al-khullah," in which there is no love for the world and what it contains, rather, all love is for Allah Ta’ala, and this very great attribute was present in Sayyiduna Muhammad, the Messenger of Allah sallallahu alayhi wa sallam. And this rank is not attained through effort and striving, because it is not acquired, rather, Allah Ta’ala bestows this great rank exclusively upon whomever He wills.

It is also established that in this world, no one is the khaleel of anyone else. This is something exclusive to our beloved Prophet Muhammad, the Messenger of Allah sallallahu alayhi wa sallam. In other words, among humanity, Allah Ta’ala made Sayyiduna Ibrahim alayhis salam His khaleel. The statement of Allah Ta’ala is: «وَاتَّخَذَ اللَّهُ إِبْرَاهِيمَ خَلِيلًا » (an-Nisa: 125). It is thus established that Allah Ta’ala made only two among mankind His khaleel: ① Sayyiduna Ibrahim alayhis salam ② Sayyiduna Muhammad, the Messenger of Allah sallallahu alayhi wa sallam. Just as Allah Ta’ala chose His khilal (intimate friends), in the same way, the Noble Prophet sallallahu alayhi wa sallam also wished to make his eminent companion, Sayyiduna Abu Bakr as-Siddiq radi Allahu anhu, his khaleel. Subhan Allah! How greatly the Noble Prophet sallallahu alayhi wa sallam is expressing the commendation of his companion of the cave!