That ye may prosper - literally, "that ye may act wisely." The connection of the two ideas of wisdom in conduct and prosperity in circumstances is noteworthy.

Keep therefore the words of this covenant, and do them,.... To do which they were laid under great obligations, through the goodness of God to them, in giving them victory over the two kings, and delivering their countries into their hands, as well as by all the favours bestowed on them in the wilderness, where they were sufficiently supplied with food, drink, and raiment; all which is made use of as a motive and argument to engage them to observe and keep the covenant the Lord made with them:

that ye may prosper in all that ye do: in all their occupations and businesses of life, in their manufactures and commerce, in the culture of their fields and vineyards, and in whatsoever they were employed in a lawful way; the word used has sometimes, the signification of acting wisely and prudently, as in Isaiah 52:13; hence the Septuagint version is, "that ye may understand all that ye do"; and so the Jerusalem Targum.

These benefits from the Lord demanded obedience and fidelity. "Keep the words of this covenant," etc. (cf. Deuteronomy 8:18). השׂכּיל, to act wisely (as in Deuteronomy 32:29), bearing in mind, however, that Jehovah Himself is the wisdom of Israel (Deuteronomy 4:6), and the search for this wisdom brings prosperity and salvation (cf. Joshua 1:7-8).

Keep therefore the words of this covenant, and do them, that ye may prosper in all that ye do.

29:1-9 Both former mercies, and fresh mercies, should be thought on by us as motives to obedience. The hearing ear, and seeing eye, and the understanding heart, are the gift of God. All that have them, have them from him. God gives not only food and raiment, but wealth and large possessions, to many to whom he does not give grace. Many enjoy the gifts, who have not hearts to perceive the Giver, nor the true design and use of the gifts. We are bound, in gratitude and interest, as well as in duty and faithfulness, to keep the words of the covenant.