Tafsir of Al-A'raf 7:90-92

{And the eminent among his people who disbelieved said} Meaning: their nobles said to those beneath them, discouraging them from faith: {If you follow Shuʿayb, then indeed you will be losers} By exchanging guidance for misguidance, as in the Almighty’s saying: “Those are the ones who have purchased error [in exchange] for guidance, so their transaction has brought no profit” (Al-Baqarah: 16). It is also said: You will lose the benefits of cheating and under-measuring, because he forbids you from them and compels you toward fulfillment and equity.

If you ask: What is the answer to the oath (indicated by the lām) in “If you follow Shuʿayb” and the answer to the conditional clause? I say: His saying, “then indeed you will be losers,” serves as the answer for both.

{Those who denied Shuʿayb} This is a subject whose predicate is {as if they had not dwelt therein}, and likewise {they were the losers}. This construction implies exclusivity; it is as if it were said: "Those who denied Shuʿayb are the ones specifically marked for destruction and eradication, as if they had never resided in their homes." This is because God saved those who followed Shuʿayb. Thus, those who denied him are the ones specifically marked for great loss, unlike his followers, for they are the winners.

In this resumption, this initial structure, and this repetition, there is an exaggeration in refuting the statement of the nobles to their followers, a belittling of their judgment, a mockery of their "advice" to their people, and an emphasis on the magnitude of what befell them.

{And he turned away from them and said, "O my people, I have certainly conveyed to you the messages of my Lord and advised you, so how could I grieve for a disbelieving people?"}