Qifā is a masculine dual imperative from the root w-q-f, related to waqafa–yaqifu: “you two, stop.” The final alif marks the dual subject.
Grammatically, the poet addresses two companions. Classical usage can occasionally employ the dual form when speaking to one person, but that literary possibility must not be confused with the form's actual dual morphology.
The address turns private reflection into an enacted scene: the poet calls to companions, asks them to halt, and draws the listener into the event.