18. Therefore. That is, because the Israelites had closed their ears to severe warning as well as to friendly admonition.
Nations. goyim (see on 1:5). The prophet summoned the Gentiles as witnesses to God’s judgment upon His people (see Isa. 1:2).
Congregation. Probably the Gentiles assembled, figuratively, as a jury. These nations were called upon to hear the sentence “upon this people,” Israel ( 19).
What is among them. Meaning either (1) the height of their wickedness and perversity, or (2) the greatness of their punishment in consequence of their depravity.