Tafsir of Yunus 10:74

{Then We sent after him} After Noah, {messengers to their people}—meaning Hūd, Ṣāliḥ, Abraham, Lot, and Shuʿayb.

{So they came to them with clear proofs} With manifest arguments that established their claims.

{But they were not to believe} Their belief was impossible, as if it were an absurdity, due to the intensity of their stubbornness in disbelief and their firm resolve upon it.

{Because they had denied it before} He means that before the sending of the messengers, they were people of ignorance who denied the truth. Thus, there was no distinction between their state after the messengers were sent and their state before; it was as if no one had been sent to them at all.

{Thus do We seal} Just as that firm sealing, We seal {the hearts of the transgressors}. The "sealing" functions as a metaphor for their obstinacy and contentiousness, for abandonment (by God) follows it. Do you not see how He attributed transgression to them and described them by it?

{Then We sent after them Moses and Aaron to Pharaoh and his chiefs with Our signs, but they behaved arrogantly and were a criminal people. So when the truth came to them from Us, they said, "Indeed, this is clear magic." Moses said, "Do you say of the truth when it has come to you, 'Is this magic?' But magicians will not succeed." They said, "Have you come to us to turn us away from that upon which we found our fathers and so that you two may have grandeur in the land? And we are not believers in you."}