Albert Barnes Commentary Psalms 107:42

"The upright shall see it, and be glad; And all iniquity shall stop her mouth." — Psalms 107:42 (ASV)

The righteous shall see it, and rejoice - They will see all these changes; they will see in their own case the proofs of divine favor. They will thus have occasion for praise.

And all iniquity shall stop her mouth - The wicked will be silenced; they will be dumb. The righteous will find, in these varied scenes, occasion for praise and joy; the wicked will be able to find no occasion for complaining or murmuring. The divine dealings will be manifestly so just, and so worthy of universal approval, that, even though the wicked are disposed to complain against God, they will be able to find nothing which will justify them in such complaints.