C. F. Keil and Franz Delitzsch on Deuteronomy 30:7

Deu 30:7

But after its conversion, the curses, which had hitherto rested upon it, would fall upon its enemies and haters, according to the promise in Gen 12:3.

Israel would then hearken again to the voice of the Lord and keep His commandments, and would rejoice in consequence in the richest blessing of its God. In the expression, ושׁמעתּ תשׁוּב אתּה (“thou shalt return and hearken”), תּשׁוּב (“thou shalt return”) has an adverbial signification. This is evident from the corresponding expression in Deu 30:9, “for Jehovah will again rejoice over thee” (lit., “will return and rejoice”), in which the adverbial signification is placed beyond all doubt.

Deu 30:8-10 contain the general thought, that Israel would then come again into its normal relation to its God, would enter into true and perfect covenant fellowship with the Lord, and enjoy all the blessings of the covenant.