يَا صُبْحُ قِفْ لَا تَطْلُعْ
O morning, stop; do not rise.
Yā is a vocative particle. Ṣubḥu is a definite singular vocative built on ḍamma, in the accusative syntactic position. Qif is an imperative with an implied second-person subject.
In “lā taṭluʿ,” lā prohibits, “taṭluʿ” is a jussive imperfect marked by sukūn, and the implied subject refers back to “morning.”
Syntax identifies command and prohibition forms. Rhetoric explains why asking morning to halt expresses a wish. The two analyses are distinct but complementary.