Yahweh asks this question to emphasize that this is something that should not continue. Alternate translation: "This should not continue, prophets declaring lies which they themselves have made up." (See: [[rc://en/ta/man/translate/figs-rquestion]])
These two phrases mean the same thing and emphasize that the false prophets made up their prophesies. Alternate translation: "prophesy things that come only from their own minds" (See: [[rc://en/ta/man/translate/figs-doublet]])