فَإِذَا فَرَغْتَ فَانْصَبْ
So when you are free, devote yourself earnestly.
Verse 94:7 shifts from the reassuring indicative to a conditional directive. Idhā faraghta supplies the circumstance; fa-nṣab provides the action to undertake.
This parallels the broad discourse movement in Ad-Duḥā: recalled favor and reassurance lead into practical conduct rather than passivity.