John Gill Commentary Jeremiah 5:20

"Declare ye this in the house of Jacob, and publish it in Judah, saying," — Jeremiah 5:20 (ASV)

Declare this in the house of Jacob
That a mighty nation should come and destroy them, and they should be servants in a strange land; or rather the words seem to be an order to declare war against the Jews, and even in their own land; and do not seem to be addressed to the prophet, but to others, seeing the words are in the plural number; see (Jeremiah 4:5) : and publish it in Judah :
the house of Jacob and Judah are the same, namely, the two tribes of Benjamin and Judah; for, as for the ten tribes, as observed on (Jeremiah 5:15) , they had been carried captive before this time: saying :
as follows: