Thus I was as a man that heareth not - The sentiment in the former verse is repeated here to show the greatness of his patience and forbearance, or to fix the attention on the fact that one who was so calumniated and wronged could bear it patiently.
And in whose mouth are no reproofs - As a man who never reproved another; who, whatever might be the wrong which he endured, never replied to it; as he would be who was incapable of reproof, or who had no faculty for reproving. The whole of this is designed to show his entire patience under the wrongs which he suffered.

No reproofs - תוכחות tochachoth, arguments or vindications; a forensic term. I was as a man accused in open court, and I could make no defense.

Thus I was as a man that heareth not,.... Any thing that is said unto him; he took no more notice of it than if he had never heard it; but bore all the railings and calumnies of men with calmness and patience;
and in whose mouth are no reproofs; as if he had nothing to say for himself, in vindication of his character, and to the refutation of his enemies; as if he had no arguments to make use of, for the conviction and reproof of his adversaries.