Albert Barnes Commentary Psalms 107:16

"For he hath broken the gates of brass, And cut the bars of iron in sunder." — Psalms 107:16 (ASV)

For he has broken the gates of brass — The immediate “reason” given here for praising the Lord is that he had broken the gates of brass, continuing the thought from Psalm 107:10-14.

In the previous part of the psalm, when giving a reason for praising the Lord, the fact that he feeds the hungry was selected (Psalms 107:9). This was because the preceding part alluded to the sufferings of hunger and thirst (Psalms 107:4–5).

Here, the fact that he had broken the gates of brass is selected because the allusion in the immediately preceding verses (Psalms 107:12–14) was to their imprisonment.

In the construction of the psalm, there is great regularity. The “gates of brass” probably refer to Babylon; and the idea is that their deliverance had been as if the brass gates of that great city had been broken down to give them free exit from their captivity. Thus, the conquest of Babylon by Cyrus is announced in similar language: I will break in pieces the gates of brass, and cut in sunder the bars of iron, (Isaiah 45:2). See the notes at that passage.