What does bal accomplish in “kallā bal tukadhdhibūna bi-l-dīn”?

Supplementary Practice 29 — Comparative Rhetoric of Sūrat al-Infiṭār and Sūrat al-Inshiqāq

• Deletes an answer to an implied question
• Exposes denial of recompense following rebuke
• Places an active participle in the accusative
• Creates a coordinate oath