يَا لَيْلُ طُلْ يَا نَوْمُ زُلْ، يَا صُبْحُ قِفْ لَا تَطْلُعْ
O night, grow long; O sleep, depart; O morning, stop—do not rise.
The poet addresses night, sleep, and dawn. “Lā taṭluʿ” is formally a prohibition directed at morning, which cannot halt its rising in obedience to a human speaker. The intended meaning is a powerful wish that dawn not arrive.
This is tamannī: expressing a desired state, not expecting an addressee literally to suspend the natural order.
The imperatives “ṭul, zul, qif” and the prohibition “lā taṭluʿ” work together to create one atmosphere of yearning.