(We will cast terror into the hearts of those who disbelieved)

This is an explanation of what preceded. The use of the "Nun" of majesty is in the manner of shifting person (iltifat), following the conventions of pride to cultivate awe. The "Sin" is for emphasizing the casting. "Al-ru'b" (terror), with a quiescent 'ayn, means fear and alarm; that is, We will throw that into their hearts.

The intended meaning of the relative pronoun refers to Abu Sufyan and his companions. Ibn Jarir recorded from al-Suddi, who said: When Abu Sufyan and the polytheists departed on the day of Uhud, heading toward Mecca, Abu Sufyan traveled until he reached part of the road. Then they felt regret and said, "What a wretched thing you have done! You killed them until only a few stragglers remained, and then you left them. Return and finish them off." So Allah Almighty cast terror into their hearts, and they were defeated. They encountered a traveler and promised him a reward, saying, "If you meet Muhammad—may Allah bless him and grant him peace—and his companions, inform them that we have gathered against them." Allah Almighty informed His Messenger—may Allah bless him and grant him peace—and he pursued them until he reached Hamra’ al-Asad. Allah Almighty revealed this verse regarding the affair of Abu Sufyan and his companions.

It is also said that the verse was revealed regarding the Day of the Confederates (al-Ahzab). In Sahih Muslim, it is narrated from Abu Hurayrah that the Messenger of Allah—may Allah bless him and grant him peace—said: "I have been granted victory through terror over the enemy." Ahmad and others recorded from the hadith of Abu Umamah: "I have been granted victory through terror [over a distance of] a month's journey, which is cast into the hearts of my enemies." It was read as "sa-yulqi" (He will cast) with a ya. Abu Ja'far, Ibn Amir, and al-Kisa'i read "al-ru'b" with a damma on the 'ayn, which is a linguistic variant. It is said that the damma is the original form and the quiescence is for ease of pronunciation; others say the quiescence is original and the damma is for assimilation.

(For what they have associated with Allah)

That is, because of their association of partners with the Essence—the Necessary Being, who gathers all attributes of perfection. He mentioned this Name (Allah) to signify the majesty that contradicts association. The first prepositional phrase relates to "We will cast," not to "terror," and the attachment of "into" does not prevent this because the meanings differ. The second relates to what is implied by it. Association was a cause for casting terror because it is among the requirements of their abandonment and the believers' victory over them; both are among the causes of terror.

#(for which He has not sent down)

That is, for that association—and it is said, for that worship—(any) authority, meaning proof. The mention of this is to indicate that what must be followed in matters of monotheism is the celestial proof, not false opinions and whims. It is called "authority" (sultan) because by it one gains strength over the opponent and dominates them. The "Nun" is supplementary; some say it is original. The mention of the non-sending down of a proof, despite the impossibility of its existence, is a case of the negation of a qualified thing due to the negation of its necessary qualification—meaning, there is no proof, so there is no sending it down. It is like his saying, describing a desert: "The rabbit does not fear its terrors, nor is the lizard seen burrowing therein," because the intent is that there is no lizard there to burrow. Thus, the intent is to negate both of them. This is like the saying: "The negative does not necessitate the existence of the subject."

What we have mentioned regarding the impossibility of the existence of proof for association is almost known from the religion by necessity. As for association regarding Lordship (rububiyyah), it is obvious; for how could Allah the Exalted command the belief that the Creator of the world is two beings sharing in necessary existence and possessing every perfection? As for association in Divinity (uluhiyyah), which is what most polytheists were upon during the time of the Messenger of Allah—may Allah bless him and grant him peace—it is because it leads to the command to believe things contrary to reality, which the polytheists believed about their idols, and which He has refuted for them.

The statement of 'Isam al-Millah: "We say the proof for association is under His power—if He willed, He would have sent it down; for if He commanded the association of idols with Him in worship, worship would have become obligatory"—I see this only as a solution for 'Isam al-Din. "There is no god but Allah"—those addressed by this, the dualists and the pagans, reject the possibility of that, as is not hidden from one who has contemplated the meaning of this blessed word. May Allah grant us death upon it, and not make us among those who associate with Allah what He has not sent down for (any) authority.

(And their abode)

That is, that to which they shall return in the Hereafter, (is the Fire; there is no abode for them) other than it.

(And wretched is the residence of the wrongdoers) (151)

That is, their residence. The noun is placed in the position of the pronoun for emphasis, providing the reason, and indicating that in their association, they are wrongdoers, placing something in other than its rightful place. "Al-mathwa" (residence) is a place of staying, on the scale of maf'al from thawayta, and its final letter is a ya. The subject of the blame is omitted—that is, "Wretched is their residence: the Fire." He did not use "the abode" (ma'wa) to signify eternity, as "staying" is inherent in "residence" (mathwa) but not in the former.