لَا تُهْمِلْ وَقْتَكَ.
Do not neglect your time.
The negative imperative particle prohibits an action and governs a jussive imperfect verb. Its grammatical form is prohibition, but the pragmatic purpose may be advice, guidance, warning or a binding command depending on who speaks, to whom and in which setting. Grammatical mood does not exhaust the utterance's rhetorical function.
Spoken by a mentor, the same wording may primarily guide a student. Issued by a responsible supervisor, it may impose a firm instruction. The wording is identical, yet the speaker–listener relationship alters its force.