Matthew Henry Commentary Isaiah 26:1-4

"In that day shall this song be sung in the land of Judah: we have a strong city; salvation will he appoint for walls and bulwarks. Open ye the gates, that the righteous nation which keepeth faith may enter in. Thou wilt keep [him] in perfect peace, [whose] mind [is] stayed [on thee]; because he trusteth in thee. Trust ye in Jehovah for ever; for in Jehovah, [even] Jehovah, is an everlasting rock." — Isaiah 26:1-4 (ASV)

"That day," seems to mean when the New Testament Babylon will be leveled with the ground. The unchangeable promise and covenant of the Lord are the walls of the church of God. The gates of this city will be open.

Let sinners then be encouraged to join the Lord. You will keep him in peace; in perfect peace, inward peace, outward peace, peace with God, peace of conscience, peace at all times, in all events.

Trust in the Lord for that peace, that portion, which will be forever. Whatever we trust in the world for, it will last only for a moment; but those who trust in God will not only find in him, but will receive from him, strength that will carry them to that blessedness which is forever.

Let us then acknowledge him in all our ways, and rely on him in all trials.