What is the verbal form and rhetorical effect of sa-yujannabuhā al-atqā?

Supplementary Practice 27 — Comparative Rhetoric of Sūrat al-Shams and Sūrat al-Layl

• First-person singular past with explicit subject
• A prohibition addressed to fire
• A passive imperfect foregrounding the result of being spared
• An exclamatory verb forming a question