Tafsir of Al-Hujurat 49:10

"The believers are but brothers" is an initiation of a statement confirming what preceded it regarding the command for reconciliation. The application of "brotherhood" to the believers is a case of tashbih baligh (eloquent simile); they are likened to brothers in terms of their affiliation to a single origin, which is the faith that necessitates eternal life. It is permissible that there is a metaphor here, likening the participation in faith to the participation in the origin of procreation, since each of them is a source of survival; for procreation is the origin of [temporal] life, and faith is the origin of eternal survival in the Gardens [of Paradise].

The fa in His saying, "so reconcile between your two brothers," serves to signal that religious brotherhood necessitates reconciliation. The use of the noun [brothers] in place of a pronoun, annexed to those commanded [to reconcile], serves to emphasize the obligation of reconciliation and to incite it. Specifying "the two" by mention serves to establish the obligation of reconciliation in matters beyond that [involving more than two people] by way of priority, due to the multiplication of strife and corruption therein. It has been said: the intended meaning of "the two brothers" refers to the Aws and the Khazraj, regarding whom the verse was revealed; each of them was called a "brother" due to their gathering under a common ancestor.

Zayd ibn Thabit, Ibn Mas'ud, and al-Hasan (with a differing report) recited it as ikhwanukum (plural, on the pattern of ghilman). Ibn Sirin recited it as ikhwatukum (plural, on the pattern of ghilmah). 'Abd al-Warith reported from Abu 'Amr all three recitations. Abu al-Fath said: The plural recitation indicates that the recitation of the majority [the dual form] has the wording of the dual but the meaning of a plural; that is, every two or more Muslims who fight. The annexation (idafa) is for the meaning of the genus, similar to labbayka and sa'dayka. The term ikhwan usually prevails in the context of friendship, while ikhwah prevails in the context of lineage, though each may be used in the place of the other.

"And fear Allah" in all that you do and all that you leave undone, among the matters which include that which you have been commanded to do regarding reconciliation. The apparent meaning is that this is a conjunction linked to "so reconcile." Al-Tayyibi said: It is a postscript (tadhil) to the discourse, as if it were said: "This reconciliation is part of God-fearing; if you practice God-fearing, this mutual bonding is included within it." It is also permissible for it to be a conjunction linked to "so reconcile," meaning: "Maintain the bond between your two brothers through reconciliation, and fear Allah, the Exalted, lest you be negligent regarding it."

"That you may receive mercy" — meaning: so that you may be granted mercy upon your God-fearing, hoping that you shall be treated with mercy for it.