Tafsir of Ash-Shams 91:13

(So the Messenger of Allah said to them): That is, to Thamud, or to the most wretched among them, according to what has been said, based on the understanding that the intended meaning is plural—a view that the phrase "and its water" does not reject, as is not hidden. The "Messenger of Allah" is Salih (peace be upon him). He is referred to by the title of "Messenger" to signal the obligation of obeying him and to clarify the extent of their insolence and persistence in tyranny. This is also the secret behind attributing the she-camel to Allah, the Exalted, in His saying, "the she-camel of Allah."

"The she-camel" is in the accusative case (nasb) as a warning (tahdhir). Its condition is not merely that the thing warned against—or the warning itself—is expressed solely by what follows it, such that it is said to be in the accusative by the estimation of "[Leave]" or "[Beware]," and not based on the [grammatical] warning. Rather, its condition is indeed that, or by way of conjunction to it, as is the case here, according to what Makki stated. The discourse entails the ellipsis of a genitive qualifier (mudaf); that is, "Beware of slaughtering the she-camel of Allah," or [it is] by way of meaning, even if it is not estimated in the structure of the speech. It was also suggested that the estimation is "Revere" or "Be committed to the she-camel of Allah," but there is nothing to that [interpretation].

"And its water": that is, and beware of [depriving her of] its water. Do not interfere by preventing her from it during her turn, and do not prioritize yourselves over her regarding it. It was said that the "and" signifies accompaniment (ma'iyya), and the meaning is: "Leave the she-camel of Allah along with her water, and do not come between them," but this is as you see. Zayd ibn Ali recited "the she-camel of Allah" in the nominative case (raf'), and it was said [it means]: "Your concern should be the she-camel of Allah and her water, so do not slaughter her and do not prioritize yourselves over her in the watering."