Tafsir of Al-Mutaffifeen 83:3

The detached pronoun in the words of the Exalted, "And when they measure for them or weigh for them, they cause loss," refers to the people mentioned previously regarding the act of taking from them; this part concerns the act of giving to them. The meaning is: when they measure out for them or weigh out for them—in a sale—they cause them loss.

The verb kāla (measure) is used with things that are measured, both with the preposition lam and without it. It has been stated in linguistics that kāla lahu and kālahu have the same meaning (to measure for him). Many scholars have explained kālahu as a case of ellipsis and connection, where the original construction was kāla lahu, then the preposition was elided and the verb directly connected [to the indirect object], as in the saying: "I have gathered for you mushrooms and truffles," and "I have forbidden you from the daughters of the desert." Similar is the proverb, "The greedy one hunts for you, not the generous one," meaning yajni laka (gathers for you) and yasīdu laka (hunts for you). It is also permitted that the speech involves the ellipsis of a noun—the measured or weighed item—with the noun taking its place; the original being: "When they measure their measured goods or weigh their weighed goods."

According to ‘Īsā ibn ‘Umar and Hamzah, the terms "measured for them" and "weighed for them" are implicit, and the pronoun hum (in kālūhum) is a nominative pronoun, serving as an emphasis for the [implicit] subject pronoun, which is the wāw. They used to pause on the two wāws in a way that clarified what they intended. Al-Zamakhshari said that it is not valid for the pronoun to be nominative for the mutaffifīn (defrauders), for the meaning would then be: "When they take from the people, they demand in full, and when they specifically undertake the measuring or weighing themselves, they cause loss." This is a contradictory statement, as the discourse concerns the action, not the agent, and as stated in al-Kashshaf, the context rejects such verbal emphasis. It is not intended to verify that the act of measuring was performed by them personally rather than by their servants, for instance.

Furthermore, the omission of the fā’ in the answer to idhā (when) rejects this; for if that were the case, the eloquent phrasing would be fa-hum yukhsirūn (then they cause loss). Therefore, it must be interpreted as a specialization, and the excuse for omitting the fā’ appears if the meaning is "they do not cause loss to the important ones," which leads to contradiction and the loss of parallelism. This interpretation of kālūhum is strongly prohibited. To interpret it as the omission of the predicate in one of the two clauses—that is, a part of the apodosis—is something that has no equivalent.

It is said that the pronoun being nominative is made unlikely by the absence of an alif after the wāw, for it is established in the science of orthography that the alif is proven after such a wāw, and the Uthmanic codex followed this convention in its equivalents. It is highly unlikely that this instance would specifically deviate from what is established and from the practice followed in other examples.

Perhaps the restriction to iktiyāl (measuring for oneself) in the context of receiving in full, and the mention of both measuring and weighing in the context of causing loss, is because the defrauders would not take what is measured or weighed except by measures, not by weights, to enable them—through measuring—to receive in full and to steal. But when they gave, they both measured and weighed, to enable them to commit fraud in both types. The conclusion is that the sublime arrangement came in this manner to correspond to those about whom it was revealed; the attribute denounces them for the excessive fraud and injustice they were committing. This is correct, whether the attribute is considered as specifying these defrauders—which is the most apparent view—or as clarifying their state, where the first [mention] refers to a conventional mental reference.

Our teacher’s teacher, the scholar Sayyid Sibghat Allah al-Haydawi, said regarding this: "Defrauding in measurement is usually done with a small amount that is often disregarded, unlike defrauding in weighing, for the slightest trick in the latter leads to a large quantity. Moreover, what is weighed is usually of higher value than what is measured. If the verse informed us that they do not leave for the people even their small, insignificant rights, it implies a fortiori that they do not leave for them the large amounts that most people—and even those of noble character—would not tolerate, except rarely. This is contrary to [the interpretation] if it were mentioned that they cause loss to the people by partial amounts, as is understood from mentioning the loss in measurement, for it would not be known from that that they also cause loss by large amounts. Rather, one might falsely imagine from the specification of the partial that they would not dare to cause loss in substantial assets. Therefore, in the second part, it is necessary to mention the loss in weighing as well, so that the verse may denounce their base deeds and decry their heinous conditions."

This was countered by the argument that this does not resolve the question, for it is permissible to ask: "Why did He not say, 'When they measure against the people, they receive in full, and when they weigh for them, they cause loss,' so that it may be known from the two correlates that they receive the large amounts in full and cause loss by the trivial amount a fortiori?" This would have been a case of iḥtibāk (mutual ellipsis).

Al-Zajjaj said the meaning is: "When they measure from the people, they receive the measure in full from them, and likewise when they weigh, they receive the weight in full." He did not mention "when they weigh [from them]" because both measuring and weighing are the means of buying and selling for what is measured and weighed. His intent, as stated by al-Tibi, is that the mention of one correlate sufficed for the other due to the indication of the subsequent correlate, which is as you can see.

It is also said that defrauders are sellers, and they usually buy a large quantity at once and then sell it in small amounts on multiple occasions. How often have we seen them buy from farmers a large quantity of grain, for example, in one day, store it, and then sell it bit by bit over many days. Since the prevailing custom was taking a large amount by measurement, only iktiyāl was mentioned in the context of receiving in full. And since what they sold varied in quantity, both measuring and weighing were mentioned in the context of giving—or [the choice of] what determines the quantity was left to the discretion of whoever buys from them—mentioning both in that context, as some choose measuring and others choose weighing. You know, however, that the premise that the prevailing custom is to take a large amount by measurement is not universally accepted, and perhaps it is so in some places and not in others. The people of our city, the City of Peace (Baghdad), do not measure or take measure at all; their custom is exclusively weighing and being weighed. The lack of reference to the measured and the weighed in both cases is—as more than one scholar has said—because the discourse is meant to clarify the bad conduct of the defrauders in taking and giving, not the specific nature of what is taken or given.