John Gill Commentary Daniel 5:22

"And thou his son, O Belshazzar, hast not humbled thy heart, though thou knewest all this," — Daniel 5:22 (ASV)

And you his son, O Belshazzar
His grandson; (See Gill on Daniel 5:1): have not humbled your heart
so as to acknowledge the most high God, and his dependence on him; to own him as his Sovereign, by whom he held his crown and kingdom, and to whom he was accountable; but, on the contrary, lifted up his heart in pride and haughtiness against him:

though you knew all this ;
either by the relation of others, his father and mother, and others; or being an eyewitness of it himself; wherefore his sin was the more aggravated, since he had had an example before him of pride being humbled in a very awful manner, and yet took no warning by it.