Charles Ellicott Commentary Isaiah 35:4

"Say to them that are of a fearful heart, Be strong, fear not: behold, your God will come [with] vengeance, [with] the recompense of God; he will come and save you." — Isaiah 35:4 (ASV)

Be strong, fear not: ... — The words are, of course, wide and general enough, but looking to the probable date of this section, we may perhaps connect them with the tone of Hezekiah’s speech in 2 Chronicles 32:7. Both king and prophet had the same words of comfort for the feeble and faint-hearted, and the ground of comfort is that the government of God is essentially a righteous government, punishing the oppressor, and saving the oppressed .