Prohibition as command or counsel

Supplementary Practice 6: Rhetorical Dialogue, Responding to Objections and Choosing the Right Expression

لَا تُهْمِلْ دَرْسَكَ.
Do not neglect your lesson.

This is a prohibitive construction. Issued by an instructor with authority, it may prohibit the action directly; offered by a concerned peer, it can work as advice or guidance.

The particle lā establishes grammatical prohibition but not, by itself, every rhetorical nuance. Speaker status, relationship, and communicative aim determine whether the speech act is directive, advisory, or another closely related use.