Jussiveness

Jussiveness is certainly a common factor of all four occurrences, but nʾ cannot be a simple verbal imperative ‘take!’ (with Samadi 115, to an unknown √*nā).

Source: wiktionary

In the same vein, the imperative reading on verbs arises from the syntactic checking of injunctive force and the pragmatic role feature of hearer – a relation that Zanuttini (2008) identifies as a Spec-head configuration between jussiveness and addressee features.

Source: wiktionary

Vowellessness of the third radical letter of imperative in verb forms 1, 4, 13, and fourteen is the result of the jussiveness of imperative by lām, […]

Source: wiktionary