Thus shall you say to them: “The gods who did not make the heavens and the earth shall perish from the earth and from under the heavens.”
Now, the reason why he bids the Israelites to speak in the Chaldee language is, because they had been led into exile, and were mingled with the Assyrians and Chaldeans. He then required from those despised exiles an open and a bold confession, as though he had said, “Even though ye are now in the most miserable bondage, and though the Chaldeans disdainfully oppress you...
The prophet Isaiah, when he prophesied of the captivity in Babylon, added warnings against idolatry and largely exposed the sottishness of idolaters, not only because the temptations in Babylon would be in danger of drawing the Jews there to idolatry, but because the afflictions in Babylon were designed to cure them of their idolatry.
Commenting on Jeremiah 10:1-16
Thus shall ye say unto them,.... The godly Jews to the idolatrous Chaldeans; and therefore this verse alone is written in the Chaldee language. The Targum prefaces it thus, "this is the copy of the letter, which Jeremiah the prophet sent to the rest of the elders of the captivity in Babylon; and if the people among whom you are should say unto you, serve...