Tafsir of Al-Hijr 15:4-5

{And it has a known decree} This sentence functions as an adjective (sifah) for "a town" (qaryah). Grammatically, the inclusion of the waw (conjunction) between them is irregular, as seen in the verse: “And We did not destroy any town but that it had [a] warner” (Ash-Shu‘ara: 208). The waw was inserted here to emphasize the inseparable nature of the attribute to the described noun. This is similar to how one says regarding a state (hal): "Zayd came to me, [while] he was wearing a garment," or "Zayd came to me, and he was wearing a garment."

{A known decree} Meaning: a written, determined decree. It refers to the town’s appointed time (ajal) which was written in the Preserved Tablet (al-lawh) and made clear. Do you not see the verse: “No nation can precede its appointed time” (Al-Hijr: 5), which occupies the place of "its decree"?

He used the feminine pronoun for "nation" (ummah) initially, then used the masculine pronoun later, alternating between the grammatical form (lafz) and the meaning (ma‘na). He said {and they cannot delay it} (wa ma yasta’khirun), omitting the prepositional phrase "from it" (‘anhu) because it is understood.