What is the wisdom behind framing the dialogue in the verse, "Said the chiefs of those who were arrogant among his people to those who were oppressed – to those among them who believed, 'Do you know that Salih is a messenger from his Lord?' They said, 'Indeed, we are believers in that with which he has been sent.' (75) Said those who were arrogant, 'Indeed, we are disbelievers in that in which you have believed.' (76)" in the form of a conversation, instead of directly stating the belief of the oppressed and the disbelief of the arrogant?

Some exegetes have mentioned benefits related to the dialogue between the arrogant and the oppressed in the story of Salih (peace be upon him):

Al-Zamakhshari said in "Al-Kashshaf": The question of the arrogant: (Do you know that Salih is a messenger from his Lord?) was a mockery, and the answer of the oppressed: (Indeed, we are believers in that with which he has been sent) was an affirmation that his sending is a known matter beyond doubt, and the dispute is concerning belief in him. And the disbelievers' answer: (Indeed, we are disbelievers in that which you have believed in) was a rebuttal to that.

Abu Al-Su'ud added: The oppressed deviated from answering (yes) to (Indeed, we are believers in that with which he has been sent) to indicate the steadfastness of their faith and the clarity of Salih's mission, and that the real question was about believing in him. And that the arrogant said: (Indeed, we are disbelievers in that which you have believed in) to show their opposition.

Ibn Ashour mentioned: The arrogant's question was for skepticism, denial, and mockery. And the oppressed's answer with the nominal sentence (Indeed, we are believers in that with which he has been sent) indicates the firmness and steadfastness of their faith, and that their deviation from answering (yes) implies their affirmation of what Salih brought, including monotheism and resurrection. And the arrogant's statement (Indeed, we are disbelievers in that which you have believed in) indicates their rigidity in disbelief, and that "that" which Salih was sent with is the object of the clause.