Albert Barnes Commentary Isaiah 51:7

"Hearken unto me, ye that know righteousness, the people in whose heart is my law; fear ye not the reproach of men, neither be ye dismayed at their revilings." — Isaiah 51:7 (ASV)

Hearken unto me, ye that know righteousness - My people who are acquainted with my law, and who are to be saved. This is addressed to the pious part of the Jewish nation.

Fear ye not the reproach of men - If we have the promise of God, and the assurance of his favor, we will have no reason to dread the reproaches and the scoffs of people .