How is the jussive recognized in the five-form verb tabʿathūhā after matā?

Zuhayr ibn Abī Sulmā: War, the Grinding Mill, and the She-Camel Metaphors (Verses 28–32)

• Adding tanwīn to the final letter
• Omitting the nūn while retaining plural wāw
• Converting the verb into a verbal noun
• Adding a dual alif