Tafsir of Al-Fath 48:21

{And others} is conjoined to the preceding [mention of spoils], meaning: He hastened for you these spoils, and other spoils {which you have not yet been able to}, which are the spoils of Hawazin at the Battle of Hunayn. He said: "You have not been able to" because of the mobility and dispersion involved in them.

{Allah has encompassed them} means: He has ordained them, taken possession of them, manifested them to you, and granted them to you as spoils.

It is permissible for {others} to be in the accusative case (nasb) due to an implied verb, explained by {Allah has encompassed them}, with the estimation: "And Allah has decreed others which He has encompassed." As for {which you have not been able to}, it is an adjective for "others." The nominative case (raf') is also possible, treating it as an initial subject (mubtada') because it is described by "which you have not been able to," and {Allah has encompassed them} is the predicate of the subject. The genitive case (jarr) is also possible, assuming an implied "Lord of."

If you ask: What is the position of His saying, Exalted is He: {And that it may be a sign for the believers} (Al-Fath: 20)?

I say: It is a parenthetical statement. Its meaning is: "And so that the restraint [of the enemies' hands] may be a sign for the believers, He did that." It is also possible that the meaning is: He promised you the spoils, so He hastened this booty and restrained the enemies to benefit you through it, and so that it may be a sign for the believers when they find the promise of Allah regarding it to be true; for the truthfulness of reports regarding the unseen is a miracle and a sign, and through that, He increases you in guidance and certainty.

{And if those who disbelieve had fought you, they would have turned their backs; then they would not find a protector or a helper. [This is] the established way of Allah which has occurred before, and you will not find in the way of Allah any change.}