Tafsir of Al-Ma'idah 5:119

(Allah said) This is a new discourse with which the narrative of what will occur on the day Allah gathers the Messengers—peace and blessings be upon them—is concluded, and its result and ultimate outcome are indicated. The past tense is used to denote certainty. The intent of Allah, the Exalted, speaking immediately after the answer of Isa (Jesus)—peace be upon him—is to indicate his truthfulness within the context of clarifying the state of the truthful ones among whose ranks he stands. Thereby, the fear he felt regarding the nature of that inquiry is also removed from him, rather than the removal of that fear being the primary purpose of the statement, as has been claimed.

(This) meaning this present day, (is a day when the truthful will benefit) meaning those who persist in truthfulness regarding the matters required of them—the greatest of which is the Monotheism we are discussing, as well as the laws and rulings related to it—from among the Messengers who spoke the truth and invited others to it, and through whom the testimony of the truthfulness of Isa—peace be upon him—is obtained, and from among the nations who believed those noble ones—peace and blessings be upon them—and followed them in creed and action. Through this, the inducement of the listeners, which is the purpose of the narrative, to believe in the Messenger of Allah, may Allah bless him and grant him peace, is realized. (From their truthfulness) meaning in what was mentioned in the world, as it is that which brings about benefit and reward on that day. It is said: [It refers to] in the Hereafter.

The intent of "the truthful" is the nations, and the intent of "their truthfulness" is their truthfulness in bearing witness to their prophets regarding the message delivered; this benefits them because they fulfilled the right of Allah, the Exalted, in it, and this is as you see. It is said: The intent is their continuous truthfulness from their worldly life until their afterlife, so that the aforementioned may serve as testimony to the truthfulness of Isa—peace be upon him—in what he said in response to the inquiry, as the context demands. The benefit is [realized] by virtue of its realization in the world, and the correspondence to what the context demands is by virtue of its establishment and the occurrence of some of its parts in the Hereafter. The continuous [state] is the general affair, which is being characterized by truthfulness, and there is no difficulty in this regarding the involvement of truthfulness in the Hereafter in the reward, nor is there a need to make truthfulness in the Hereafter a condition for the benefit of worldly truthfulness and being rewarded for it. Perhaps what has preceded is sufficient, as is not hidden from the observer. It is said: The intent of "the truthful" is the prophets, and "their truthfulness" is their truthfulness in the world by conveying [the message], and the course of the verse is meant to testify to his—peace be upon him—truthfulness in his saying: "I told them nothing except what You commanded me." You know that this purpose is achieved even with a generalized interpretation, and more.

It is also said: The intent of truthfulness is truthfulness in the world, but the intent of "the truthful" is the nations, and the speech is intended to refute the presentation of forgiveness [that Isa asked for] before Him, Glorified be He. It is as if it were said: This is a day when their truthfulness benefits the truthful, and nothing else; therefore, there is no forgiveness for these [others]. It is not hidden that the generalized interpretation does not contradict the speech being intended for what was mentioned, assuming the latter is accepted.

The demonstrative pronoun is the subject (mubtada’), and (day) with a damma (nominative) is the predicate—this being the reading of the majority. Nafi‘ alone read (day) with a fatha (accusative) as an adverbial time for "said," and (this) is a subject whose predicate is omitted—meaning: the speech of Isa—peace be upon him—or [it is] truth, or something similar—or it is an established adverb acting as a predicate. The meaning is: This which has passed regarding the answer of Isa—peace be upon him—or the inquiry and the answer, occurs on a day when [it] benefits. It is permissible that "this" is the subject and "day" is the predicate, and it is built upon the fatha on the basis that an adverb is built upon it when it is annexed to a verbal sentence, even if it is inflected; this is the school of the Kufans, and Ibn Malik and others preferred it. The Basrans do not permit the building [of the adverb] unless the sentence it is annexed to begins with a past verb, as in the saying: "At the time I reproached gray hair for youth." They append the negated verb to this, and they explain this reading according to one of the previous perspectives. Al-A‘mash read (day) with a damma and tanwin, as the predicate of "this," and the sentence after it is its description by omitting the relative pronoun. It was also read (their truthfulness) in the accusative, so that the doer of "benefits" is the pronoun of Allah, the Exalted, and "their truthfulness," as Abu al-Baqa said, is either for its sake (li-sidqihim) or accusative through the removal of the preposition (bi-sidqihim), or it is an emphatic verbal noun, or a direct object in the sense of "they manifest truthfulness," as you say: "I confirmed him in fighting," meaning: they realize the truth.

(For them are Gardens underneath which rivers flow, abiding therein forever) is an explanation of the benefit, and for this reason, it is not conjoined to it. It is as if it were said: What benefit is there for them? It was answered: For them is everlasting bliss and an eternal reward. His saying, the Exalted: (Allah is pleased with them) is a clarification that He, the Exalted, bestowed upon them something other than what was mentioned, which is His pleasure—Mighty and Majestic is He—beyond which there is no end, as His saying, the Exalted, indicates: (And they are pleased with Him), for there is nothing more precious than that for which the necks of hopes might yearn. (That) is a reference to the attainment of His pleasure—Glorified be His state—as some of the verifiers have chosen, or to all that has preceded, as he chose in al-Bahr, and what is narrated from al-Hasan points to this: (the great attainment 119), which the scope of description cannot encompass, and for which no equal goal can be reached at all.