Tafsir of Al-Baqarah 2:270

(Or you vow any vow) whether related to wealth or actions, with or without a condition, in obedience or disobedience. A vow (nadhr) is the firm resolve of the heart upon something and committing oneself to it in a specific manner. It is said: Its origin is fear, because a person commits to it out of fear of falling short or fear of a dangerous matter occurring. From this is "the vow of blood" (nadhr al-dam), which is the oath to shed it due to fear of the harm of its owner. Amr ibn Ma'dikarib said: "They vow my blood, and if I encounter them, I am the most intense." Its verb is conjugated like daraba and nasara. According to Yunus, as narrated by al-Akhfash, the Arabs say: "He vowed a vow upon himself" (nadhara 'ala nafsihi nadhran) and "I vowed my wealth, so I vow it a vow."

(Then indeed, Allah knows it) This is a metonymy for His, the Sublime’s, rewarding for it; otherwise, it is already known. The fa (then) is introduced into the answer if "whatever" (ma) is conditional, or it is a connective in the predicate if it is relative. The singular pronoun is used—despite the fact that the object of knowledge is plural—because the reference is unified, based on the fact that the conjunction is with the word "or," which is for one of two things. Ibn Atiyyah said: "The singularity is in consideration of the mentioned [vow]." It is as if he did not consider the mentioned [expenditure] in view of the reference being the expenditure and the vow as mentioned, rather than the verbal nouns understood from their two verbs, which are the two conjoined by "or." Even if one concedes that the conjunction of two verbs necessitates the conjunction of the two verbal nouns, one should not consider them either, because the pronoun is definitely masculine while they are masculine and feminine; considering one without the other is a preference without a preferrer.

The weakness in this is not hidden, for such a pronoun may be considered according to the state of the preceding element, observing precedence—as in His saying: “And when they saw a transaction or a diversion, they dispersed to it”—and it may be considered according to the state of the succeeding element, observing proximity—as in His saying: “And whoever earns a fault or a sin and then blames an innocent person for it.” Both are permissible and common in eloquent speech, and what we have here is from the latter, provided the mentioned [vow] is considered explicitly. Insisting on interpretation in all instances is an imposition that can be dispensed with, as is not hidden. Indeed, some have permitted the return of the pronoun to "whatever" (ma), but only on the assumption that it is a relative pronoun, as more than one have stated.

(And for the wrongdoers) i.e., those who place things in other than the positions where they rightly belong. Thus, it includes those who spend out of showing off (riya'), obligation (mann), and harm; those who seek out the impure for spending; those who spend in falsehood; those who vow in disobedience; and those who refrain from fulfilling what they vowed in righteousness or are stingy with charity from what Allah the Exalted has granted them of His bounty. Abu Sulayman al-Dimashqi restricted it to those who spend with obligation, harm, and showing off, and those who are wasteful in disobedience; Muqatil restricted it to the polytheists. Perhaps generalization is more appropriate.

(There are no helpers) i.e., no aids to help them against the punishment of Allah the Exalted, neither through intercession nor defense. It is the plural of nasir (helper), like habib and ahbab (beloved/beloveds), or nasir like shahid and ashhad (witness/witnesses). Bringing it in the plural form is by way of correspondence; thus, the objection that the negation of the plural does not necessitate the negation of the singular (the helper) does not apply, for the latter is the intended meaning. The claim that this is only needed if "of" (min) is considered redundant is groundless, for you may consider it partitive—i.e., "nothing of the helpers [exists for them]"—as is clear. The sentence is an inauguration establishing the threat contained in the substance of what preceded it.

The negation of there being any helper for the wrongdoer absolutely—according to the opinion of Muqatil—is obvious. As for the assumption that "wrongdoers" is taken generally, or specifically as Abu Sulayman said, it is necessary to say that the verse is phrased in the way of intimidation, for the sinner who is not a polytheist, regardless of the nature of his sin, may have a helper who intercedes for him before his Lord. The verse is used as evidence for the legitimacy of vowing and the obligation to fulfill it, provided it is not in disobedience; otherwise, there is no fulfillment. Al-Nasa’i recorded from Imran ibn al-Husayn that the Messenger of Allah (peace be upon him) said: "Vows are of two types: Whatever vow is in the obedience of Allah the Exalted, that is for Allah the Exalted, and in it is fulfillment. And whatever vow is in the disobedience of Allah the Exalted, that is for Satan, and there is no fulfillment in it; one should perform that which expiates the oath." Detailed discussion on vows will follow later, if Allah wills.