Why is the repeated “Fa-bi-ayyi ālāʾi rabbikumā tukadhdhibān” purposeful?

Supplementary Comprehensive Examination — Advanced Arabic Texts and Evidence-Based Rhetorical Analysis

• It introduces a new past tense each time
• It is required only for rhyme
• It renews reminder and reproof after successive signs
• It turns the clause into a non-declarative noun