Tafsir of Al-Mu'minoon 23:15

"Then, after that" — that is, after what has been mentioned of the wondrous matters, as indicated by the meaning of distance in the demonstrative pronoun, which signifies the high rank of that which is referred to, its elevated status in merit and perfection, and its being—due to that excellence—treated like a tangible object—"you shall surely die."

"That is, you are bound to reach death inevitably," as indicated by the nominal nature of the sentence, the particle inna (verily), the lam (of emphasis), and the form of the active participle (ism al-fa'il), which denotes permanence. Zayd ibn Ali (may Allah be pleased with them both), Ibn Abi 'Ablah, and Ibn Muhaysin read it as lamaytun (plural of mayt). As for the reading lamaytun (with an alif), it is an active participle intended to denote occurrence. Al-Farra and Ibn Malik said: "The form mayit is only used for the future."