Tafsir of Az-Zumar 39:27

{An Arabic Qur’an} This is a confirmatory state (ḥāl mu’akkadah), similar to your saying: "Zayd came to me as a righteous man and a rational human being." It is also permissible for it to be in the accusative case as an expression of praise.

{Without any crookedness} Meaning: upright, free from contradiction and inconsistency.

If you ask: Why was it not said "straight" (mustaqīman) or "not crooked" (ghayr mu’wajj)? I reply: There are two benefits in this:

1. The negation of any crookedness whatsoever, as He said: "And has not placed therein any crookedness" (Al-Kahf: 1).
2. The term ‘iwaj (crookedness) is specific to abstract concepts, not physical objects.

It has been said that what is meant by ‘iwaj is doubt and ambiguity. A poet recited: And there has come to you a certainty, without any crookedness, From the God, and a statement that is not belied.

{Allah presents an example: a man belonging to partners who are quarreling, and a man belonging wholly to one man. Are they equal in comparison? Praise to Allah! But most of them do not know. Indeed, you are to die, and indeed, they are to die.}