Be not afraid, i.e. thou shalt not be afraid. For that it is a promise, seems most probable from the context; only it is for greater emphasis delivered in the form of a precept; I allow thee and require thee not to be afraid, which is both thy duty and privilege. Of sudden fear; for sudden and unexpected evils are most frightful and grievous. And fear is here put for the evils feared, as Proverbs 1:26,27, and oft elsewhere. The desolation of the wicked; either,
1. Actively, which they bring upon thee. Or, rather
2. Passively, which befalls them, when the Lord cometh out of his place to punish the inhabitants of the earth for their iniquity, as it is expressed, Isaiah 26:21; and thou mayst be apt to fear lest thou shouldst be involved in the common calamity; but fear not, for God will then hide thee in his chambers, as he promised, Isaiah 26:20.