John Calvin Commentary Lamentations 3:46

"All our enemies have opened their mouth wide against us." — Lamentations 3:46 (ASV)

He repeats what he had said: that the people were an offscouring, or scrapings, or sweepings, and also a refuse. The last word is, indeed, in the infinitive mood, מאוס, maus, but it is to be taken as a noun. They had become all this because they had as many enemies as neighbors, for we know that the Jews were hated by all the neighboring nations.

Consequently, they had become a refuse and filth among all people, for with an open mouth their enemies spoke furiously against them. For the open mouth means that they spoke insolently and took the liberty of cursing them all, as has been stated elsewhere. Now, it was the bitterest thing for the miserable people when they found that the reproaches and taunts of enemies were added to their calamities, for we know how grievously reproach wounds those who are already afflicted.