Tafsir of Ar-Rahman 55:9

"And establish the weight with justice" means: perform your weighing with fairness. Al-Raghib said: This is an indication to observe moderation in all the actions and words that a human pursues. Mujahid stated that the meaning is: keep the tongue of the balance straight with justice when you intend to give or receive. Sufyan ibn ‘Uyaynah said: Establishing it is with the hand, and the justice (al-qist) is with the heart.

It is apparent that the sentence is a conjunction to the negated sentence before it. It does not harm that this is imperative (insha’i) while the former is declarative (khabari), because, through its interpretation as a single concept, it is divested of the meaning of a request. Some considered the "la" in the previous [verse] as absolute negation, out of a desire for consistency.

"And do not diminish the balance" (i.e., do not cause it a loss, for its right is to be level, as that is the purpose of its placement). The term "the balance" was repeated without using a pronoun, as would have been required by the apparent grammatical structure, to emphasize the recommendation, confirm the command to use it, and urge toward it. Indeed, in the three sentences, there is a repetition that holds meaning for that purpose.

It was recited: wa-la tuksiru (do not diminish) with a fatha on the ta and a damma on the sin. Zayd ibn ‘Ali and Bilal ibn Abi Burdah recited it with a fatha on the ta and a kasra on the sin. Ibn Jinni and the author of al-Lawamih reported from Bilal that he recited it with fatha on both. Al-Zamakhshari explained this by assuming the origin was "do not diminish [in] the balance," thus omitting the preposition, and [arguing] that the verb's origin is intransitive, as it only appears as such. Abu Hayyan critiqued this, stating that khasara has indeed appeared as a transitive verb, such as in the Almighty’s saying: "They have lost their souls" and "He has lost this world and the Hereafter," so there is no need to claim omission and connection. It was answered that, even on the premise that it is transitive here, one must assume omission and connection, meaning the object is omitted—i.e., "do not lose yourselves in the balance," meaning do not be among the losers on the Day of Resurrection because of the balance by failing to observe what is required therein.

Al-Raghib permitted interpreting the verse according to the well-known recitation in a similar manner, saying: "The saying of the Almighty, 'And establish the weight with justice and do not diminish the balance,' may be an indication to pursue justice in weighing and to abandon oppression in what is transacted therein. It may also be an indication to perform that by which one will not be a loser in the Resurrection, thus being among those of whom He, Glory be to Him, said: 'And as for him whose scales are light.'" Both meanings are interconnected. It was also said that the meaning is based on transitivity by assuming an added noun, i.e., "the item weighed in the balance," or by treating "the balance" as a metonymy for the thing being weighed. Reflect upon this, and do not be heedless.