ثُمَّ مَآ أَدْرَىٰكَ مَا يَوْمُ ٱلدِّينِ ۝١٨ What does ثُمَّ do here?

Surah Al-Infitar — Part 3

• It negates the clause
• It coordinates and repeats the warning
• It makes the verb jussive
• It is a preposition