“[Tell them] I lived a whole lifetime amongst you (you know who I am) -- can't you think?”
This ayah is part of the Qur'an's rebuttal to the false accusations described at this event -- the Prophet ﷺ pointing out he had lived a full lifetime among them with a known, trusted character before any of this.
“Say, 'Who provides you with sustenance out of the heaven and the earth? Who holds mastery over your hearing and sight? Who brings forth the living from the dead and the dead from the living? Who governs all affairs of the universe?' They will surely say, 'Allah.'”
“Make their hearts hard so that they never have Iman until they see the Punishment come down on them.”
The post directly quotes Musa (AS)'s prayer as preserved in this ayah (Q10:88) -- asking Allah to harden the disbelievers' hearts until they see the punishment.