Tafsir of Al-Ahqaf 46:21

Since the people of Mecca were immersed in the pleasures of the world and turned away from faith and what the Messenger (may Allah bless him and grant him peace) brought to them, it was appropriate to remind them of what happened to the first Arabs—those who were more affluent, stronger in power, and greater in prestige than them, yet upon whom torment was unleashed because of their disbelief. By citing examples and the stories of those who preceded, the ugliness and beauty of things are recognized. Thus, the Almighty said to His Messenger (may Allah bless him and grant him peace):

(And remember)—O Messenger, for the disbelievers of Mecca—(the brother of ‘Ad), who is Hud (peace be upon him).

(When he warned his people)—This is a badal ishtimal (appositional) of the aforementioned; meaning, the time of his warning them.

(In Al-Ahqaf)—This is the plural of hiqf, which refers to an elongated, curved, and winding sand dune. It is said, "The thing ihaqwaqa," meaning it became crooked. They were Bedouins, possessors of tents and pillars, dwelling among the sands, overlooking the sea in a land called al-Shihr, in the territory of Yemen, as stated by Ibn Zayd. Ibn Abbas (may Allah be pleased with them both) said it is the area between Oman and Mahra; and in another narration from him, Al-Ahqaf is a mountain in the Levant. Ibn Ishaq said their dwellings stretched from Oman to Hadramawt. Ibn Atiyyah said the correct view is that the land of ‘Ad was in Yemen, and to them belonged Iram of the pillars—the discussion regarding Iram and the truth of the matter will follow, God willing.

(And warners have passed away)—That is, the messengers, as is widely held. It is also said that it refers to everyone who warns, and the term nudhur (warners) is the plural of nadhir, meaning mundhir (one who warns). It is permissible for nudhur to be the plural of nadhir in the sense of indhar (warning), making it a verbal noun (masdar); it is pluralized because warnings vary according to the subject being warned against. However, it has been objected that pluralizing it this way contradicts standard linguistic rules, and there is no pressing need for such an interpretation.

(From before him and from behind him)—Meaning, from before he (Hud, peace be upon him) came, and from after him. It has also been recited as bih (in it), and were it not for that, the inverse would be permissible. The apparent meaning is that it refers to the warners who preceded him and those who came after him. According to Ibn Abbas, it means the messengers who were sent before him and those who were sent in his time; thus, the meaning of "from behind him" is from after his warning. Attaching "from behind him" (the time after) to what precedes it (the time before) is like the poetic expression: “I fed it fodder and cold water” (where the second verb is implied). In the context of the verse, it means: "Warners have passed away from before him, and [others] came from behind him." It is also said that this is a case of mushakala (stylistic adaptation), or a metaphorical expression (isti‘ara bil-kinaya). It may also be that it brings those who are yet to come into the fold of the past, by treating their occurrence as a certainty. There is a hint of combining the literal and the metaphorical here. It is also permissible to say that the past tense is used considering the fixity of events in Allah’s knowledge; meaning, the warners have passed away in Allah’s knowledge—that is, the passing of those who came before and those who were yet to come was already established in His knowledge.

The sentence is either a circumstantial state (hal) from the agent of "warned"—meaning, while he warned, informing them of the passing of the warners—or from its object, meaning while they were cognizant of his informing them. This is close to the style of the Almighty’s saying: "How can you disbelieve in Allah when you were lifeless?" It is also permissible for the meaning to be that he warned them during an interval between messengers, which is also a circumstantial state according to the interpretation of Ibn Abbas. The people's knowledge can be attributed to his informing them, their witnessing the conditions of those in his time, and their hearing of the conditions of those who preceded them.

As for the interpolation between the explained—that is, "warned his people"—and the explanation—that is, the Almighty’s saying, "that you worship none but Allah"—it is because the prohibition of a thing is a warning of its harm. It is as if it were said: "Remember the time Hud warned his people with what the messengers before and after him had warned, which is that you worship none but Allah." This serves as a reminder that this is an established warning, ancient and modern, upon which all the messengers (peace be upon them) have agreed unanimously. This confirms the Almighty’s saying, "And remember," and confirms His saying, "warned his people"; this is why it is placed in the middle. It is also an object of the remembrance, unlike if it were a circumstantial state (hal), in which case it would be a secondary qualifier. This approach is superior to the one preceding it, as established in al-Kashf.

Some have permitted viewing it as attached to "warned"—meaning, "and inform them of that." This is as you see. "An" (that) has been interpreted as explanatory, because it signifies the meaning of speech without its literal letters, which is "warning," and the explained is its implied object. It is also permissible for it to be a verbal particle (masdariyyah) or a softened form of the heavy anna; thus, before it is an implied preposition attached to "warned," meaning: "Warn them that they should worship none but Allah."

(I fear for you the punishment of a tremendous day.)

This is an attribute of "day." Its "tremendousness" is a metaphor for it being terrifying, because terror is a necessary concomitant of it. The day being terrifying is due to the terror of the punishment it contains, so the attribution therein is metaphorical. There is no need to make it an attribute of the punishment, with the genitive case (jarr) being due to proximity (jiwar). The sentence is an explanatory initiation for the prohibition, and it is understood: "I fear for you that [punishment] because of your polytheism."