Tafsir of An-Nisa' 4:13

(Those) refers to the mentioned rulings concerning the affairs of orphans, inheritance, and others. Ibn Abbas—may Allah be pleased with both of them—limited it to [the rulings of] inheritance.

(Limits of Allah) refers to His laws, His obedience, His details, or His stipulations. They are called "limits" (hudud) due to their resemblance to them, in the sense that it is not permissible for the legally responsible person (mukallaf) to transgress them to anything else.

(And whoever obeys Allah and His Messenger) in what He has commanded of rulings or what He has ordained of obligations. The use of the noun [Allah and His Messenger] in the place of a pronoun is due to what has previously been pointed out.

(He will admit him into gardens)—the accusative case indicates an adverb of place according to the majority, or the object of the verb according to al-Akhfash.

(Under which flow), that is, under their trees and buildings—a discussion on this has already passed.

(Rivers), meaning their water.

(Abiding eternally therein) is a prospective state (hal muqaddara) derived from the object of "He will admit him," because eternity occurs after admission. It is similar to your saying: "I passed by a man having a falcon that he will hunt with tomorrow." The plural form is used to observe the meaning of "whoever" (man), just as the singular pronoun is used to observe its wording.

(And that), meaning admission into the gardens in the aforementioned manner, (is the great attainment), that is, success and the achievement of good—either in itself, or in addition to acquiring the inheritance, as has been said. The sentence is a parenthetical clause.