Matthew Henry on Isaiah 35:1-4

Judea was prosperous in the days of Hezekiah, but the kingdom of Christ is the great subject intended. Converting grace makes the soul that was a wilderness, to rejoice with joy and singing, and to blossom abundantly. The feeble and faint-hearted are encouraged. This is the design of the gospel. Fear is weakening; the more we strive against it, the stronger we are, both for doing and suffering; and he that says to us, Be strong, has laid help for us upon One who is mighty. Assurance is given of the approach of Messiah, to take vengeance on the powers of darkness, to recompense with abundant comforts those that mourn in Zion; He will come and save. He will come again at the end of time, to punish those who have troubled his people; and to give those who were troubled such rest as will be a full reward for all their troubles.