Sforno on Deuteronomy 30:8/ספורנו על דברים ל׳:ח׳

1ואתה תשוב, not from the root שוב to return, but from the root ישב, i.e. you will sit at ease, undisturbed. Compare Isaiah 30,15 בשובה ונחת. This period will be ushered in by the arrival of the Messiah after the hostile nations have been eliminated. Moses contrasts what will happen to those nations and what will happen to the Jewish people at that time. G’d will never exile you again. All this has been spelled out by Jeremiah 4,1 when he said:אם תשוב ישראל....אלי תשוב....ולא תנוד, “if you return Israel….return to Me, and you do not waver, …nations shall bless themselves by you, etc.”

2ועשית את כל מצוותיו אשר אנכי מצוך היום, not adopting any new religious rites or philosophies.