This is the word that came to Jeremiah from the LORD:
The sum of what is here taught is, that as the Jews gloried in God’s singular favor, which yet had been conferred on them for a different purpose, even that they might be his sacred heritage, it was necessary to take from them a confidence of this kind; for they at the same time heedlessly despised God and the whole of his law.
The prophet is here sent to the potter's house (he knew where to find it), not to preach a sermon as before to the gates of Jerusalem, but to prepare a sermon, or rather to receive it ready prepared. Those needed not to study their sermons that had them, as he had this, by immediate inspiration.
Commenting on Jeremiah 18:1-10
The word which came to Jeremiah from the Lord, saying. The word of prophecy, as the Targum: this is a distinct prophecy from the former, though it may be connected with it; it referring to the destruction threatened in the latter part of the preceding chapter. The word which came to Jeremiah from the Lord, saying.