About what rest did he tell to them?
Radak: If you will hear Hashem's word and do His Mitzvos, you will have rest in your land and not be exiled from it.
Malbim: You will have bodily rest 1 .
Malbim: One does not accept rebuke if he does not understand, or because he was told matters hard to fulfill, e.g. to afflict himself or part with his money. Here, the Navi spoke clearly in his nation's language, and asked them only to rest and not steal, and even so they did not listen!
What is the meaning of "Hanichu la'Ya'ef"?
Rashi: Do not steal from the weary.
Radak: He told the Kohanim and Nevi'im to give rest to the weary. I.e. Yisrael who are weary from many Tzaros that will come on them, instruct them Hashem's word, in which they will have rest. Do not make them stray with your lies and rashness.
Malbim: Do not steal from one who sighs due to those who oppress him with force.
