What does the move from fa-atharna dust to fa-wasaṭna a group show?

Supplementary Practice 25 — Comparative Rhetoric of Sūrat az-Zalzalah and Sūrat al-ʿĀdiyāt

• An unnecessary denial of the previous assertion
• A switch of the subject from humans to the earth
• The direct beginning of a conditional answer
• Connected motion from raised dust to reaching the midst of the group