Doubly Weak Roots and the One-Letter Command

Comprehensive Final Revision: Root Classes, Morphological Changes, Conjugations, Nouns and Verb-Form Semantics

Separated doubly weak (lafīf mafrūq): first and third radicals are weak, as in وَقَى / يَقِي. Adjacent doubly weak (lafīf maqrūn): second and third radicals are weak, as in طَوَى.

PositionFormProcess
Rootو ق يTwo separated weak radicals
PastوَقَىFinal weak change
PresentيَقِيInitial wāw deleted
Jussiveلَمْ يَقِFinal weak letter deleted
CommandقِBoth changes are reflected

قِ نَفْسَكَ الشَّرَّ
Translation: Protect yourself from evil.

A one-letter command is not a one-letter lexical root.