They are corrupt, and speak wickedly concerning oppression: they speak loftily.
Read Chapter 73
Augustine of Hippo
AD 430
11. "They have thought and have spoken spitefulness" (ver. 8). But men do speak spitefulness even with fear: but these men how? "Iniquity on high they have spoken." Not only they have spoken iniquity; but even openly, in the hearing of all, proudly; "I will do it;" "I will show you;" "thou shalt know with whom thou hast to do;" "I will not let thee live." Thou mightest have but thought such things, not have given utterance to them! Within the chambers of thought at least the evil desire might have been confined, he might have at least restrained it within his thought. Why? Is he perchance lean? "There shall go forth as if out of fatness the iniquity of them." "Iniquity on high they have spoken."
High. With impudence; (Menochius) boldly despising others, (Worthington) from their exalted station. (Berthier)
They even dare to contend with the Almighty. (Haydock)