فَبِأَيِّ آلَاءِ رَبِّكُمَا تُكَذِّبَانِ
Which of your Lord’s favours will you both deny?
Interrogation, repetition, preposing and ellipsis describe forms or operations, not one fixed communicative aim. Ar-Raḥmān’s refrain challenges denial, whereas Al-Ḥujurāt’s shocking question condemns backbiting.
A good analysis names the device, identifies relevant addressees and syntax, and explains the local purpose. Memorising a figure’s name is the beginning, not completion, of rhetorical reasoning.