Tafsir of Al-Isra 17:38

"All of that"—the traits mentioned in the folds of the preceding commands and prohibitions, which resolve into over twenty—"was its evil"—that is, what was forbidden among them, such as setting up another deity alongside Allah, worshipping other than Him, saying "fie" (ta'fif), rebuking, squandering, keeping one's hand chained to one's neck, extending it fully, killing children for fear of poverty, killing a soul which Allah has forbidden except by right, the guardian's excess in retaliation, pursuing what one has no knowledge of, and walking upon the earth exultantly. The genitive construction here is of the "lam" type, signifying the inclusion of the part within the whole—"in the sight of your Lord, detested."

This means it is hated, even if it is intended by Him, Exalted is He, through creational will (irada takwiniyya); for otherwise, it would not have occurred, as indicated by the saying of the Prophet (peace and blessings be upon him): "What Allah wills occurs, and what He does not will does not occur." This will is neither synonymous with nor does it necessitate approval, lest the contradiction of the two opposites—the aforementioned will and the detestation—be joined, as the Mu'tazila claim. This is a completion of the rationale for all the forbidden matters. Describing them with absolute detestation, even though most of them are major sins, is to signal that mere detestation in the sight of Allah is sufficient to render abstention from them obligatory.

Directing the reference to the whole and then specifying some is because it is said that the aforementioned part is not mentioned as a collective whole, but in a mixed manner for a specific nuance. This contains an intimation that what remains is pleasing to Him, the Exalted. The reason He did not explicitly state this is to signal that it is already understood. Others say it is out of concern for the importance of repelling the prohibitions, as they say that "clearing away" is prioritized over "adorning," and preventing corruption is more important than attracting benefits. It is also permissible that the genitive construction be explanatory, and "that" refers either to all that preceded—whereby their opposites are derived from the commands, as they are likewise forbidden, similar to the words of the Exalted: "Do not associate anything with Him, and be good to parents," following His words, "Say, 'Come, I will recite what your Lord has forbidden you'"—or it refers only to what was explicitly forbidden.

The two Hijazis and the two Basrans read it as sayyi'atun (a bad deed), with a fat'ha on the hamza and a feminine suffix, in the accusative case as the predicate of kana (was). The reference here is to what was forbidden explicitly and implicitly, or explicitly only. As for makruhan (detested), it is said to be an appositive (badal) to sayyi'atun, and the correspondence between the appositive and that for which it is substituted is not strictly required. This has been criticized on the basis that a derived (mushtaq) appositive is rare. It is also said that it is an adjective of sayyi'atun interpreted according to its meaning, for it carries the sense of sayyi'an (bad/evil), as has been recited; or that sayyi'a has lost its adjectival sense and is treated like a noun, meaning "a sin"; or that the adjective is applied to a masculine noun, meaning "a detested affair." It is also said that it is another predicate of kana, and it is correct that its predicates may be multiple. It is also said to be a circumstantial qualifier (hal) to the hidden pronoun in kana or in the prepositional phrase, based on the assumption that it is an adjective for sayyi'atun and not connected to makruhan, in which case its pronoun is hidden within it, and the state (hal) in this case is emphatic.

You know that the hidden pronoun of sayyi'a is feminine, so making makruhan a circumstantial qualifier for it is like making it an adjective for sayyi'a, requiring interpretation. As for implying a masculine as in the verse, "Nor a land that has sprouted its plants," the flaw in that is not hidden. It is narrated from Abu Bakr al-Siddiq (may Allah be pleased with him) that he read it as sha'nuhu (its affair).