Tafsir of Al-Anbiya' 21:27

(They do not precede Him in speech): Meaning, they do not say anything until He, the Exalted, has said it or commanded them to say it, as is the custom of well-mannered servants. In this, there is an alert to the perfection of their obedience and their compliance with His command—may He be glorified and exalted—and their refined conduct toward Him, the Exalted. The linguistic origin is "their speech does not precede His speech, the Exalted." The act of preceding is attributed to them in relation to Him, the Exalted, treating their preceding of His word, glorified be He, as equivalent to them preceding Him, the Mighty and Majestic, to further emphasize their transcendence above such an act and to alert to the extreme repulsiveness of such preceding, which is an allusion to those who say what He, the Exalted, has not said. The speech is made the object of the preceding and the instrument by which it occurs. The lam (in bil-qawl) substitutes for the genitive construction (idafa) to the pronoun, according to the Kufan school, for the sake of specifying the intent and avoiding repetition.

It is also recited as la yasbuqunahu (precede Him), with a damma on the ba, treating it as a case of contest or struggle (mughalaba); it is said, "He contested me, so I preceded him (sabaqtuhu) or outpaced him (asbaqtuhu)." This form requires the damma on the medial letter of the present tense verb unless the medial or final root letter is a ya. In this reading, there is a greater sense of the repulsiveness of preceding, indicating that whoever lets his speech precede the speech of the Exalted has effectively set himself up to compete with Him, the Exalted, in precedence. It serves as a further declaration of their transcendence above what has been negated of them, by clarifying that such an act in their view is equivalent to the state of being defeated after a struggle. How, then, could it be imagined that such a thing could emanate from them, when they act only by His command?

This is a clarification of their submissiveness to Him, the Exalted, in deeds, following the clarification of their submissiveness to Him, glory be to Him, in speech. It is as if it were said: They speak by His command, and they act by His command, not by the command of anyone other than Him, the Exalted, at all—meaning they do not act of their own accord. The restriction (hasr) derived from the placement of the prepositional phrase (bi-amrihi) applies relative to anything other than His command, not relative to the command of someone other than Him, the Exalted.