Why does it say "v'Odenu Lo Yashuv"?
Rashi: Yirmeyah still did not want to return. Hashem told him, return to Gedalyah, who was appointed over the poor people who remained. They need you like the other exiles do.
Radak: Yirmeyah did not yet say that he will return; Nevuzaradan understood that he intends to return. He said, since you intend to stay, return to Gedalyah and dwell with him. Stay wherever it is straight in your eyes to stay - with Gedalyah where he is, or anywhere else in the land that you choose to dwell there - do like you desire.
Radak citing Targum Yonasan: If you do not desire Lemeisav 1 , return to Gedalyah.
Malbim: If you think that the exiles will return to Eretz Yisrael to Gedalyah, whom Melech Bavel appointed [to rule] in the land, and you will return with them, and you intend to go to Bavel only in order to return with them, [you err]. They will not return at this time! If you want to return, "Shuvah" (return by yourself).
Lemeisav can mean to dwell, sit or return. Here it means, [if you do not want] to dwell [in Bavel], or [if you do not want] to return [with me to Bavel]. (PF)
What are "Aruchah u'Mas'es"?
Rashi citing Targum Yonasan: Both are gifts. Radak - two expressions are used to teach that he gave two kinds of gifts.
Malbim: Aruchah is a constant ration to finance him.
