That he may establish thee to day for a people unto himself, and that he may be unto thee a God, as he hath said unto thee, and as he hath sworn unto thy fathers, to Abraham, to Isaac, and to Jacob.

Wesley's Notes

29:13 That he may establish thee - Here is the summary of that covenant whereof Moses was the mediator, and in the covenant relation between God and them, all the precepts and promises of the covenant are included. That they should be established for a people to him, to fear, love, obey, and be devoted to him, and that he should be to them a God, to make them holy and happy; and a due sense of the relation we stand in to God as our God, and the obligation we are under to him as his people, is enough to bring us to all the duties, and all the comforts of the covenant. And does this covenant include nothing spiritual? nothing that refers to eternity?

Matthew Henry's Concise Commentary

29:10-21 The national covenant made with Israel, not only typified the covenant of grace made with true believers, but also represented the outward dispensation of the gospel. Those who have been enabled to consent to the Lord's new covenant of mercy and grace in Jesus Christ, and to give up themselves to be his people, should embrace every opportunity of renewing their open profession of relation to him, and their obligation to him, as the God of salvation, walking according thereto. The sinner is described as one whose heart turns away from his God; there the mischief begins, in the evil heart of unbelief, which inclines men to depart from the living God to dead idols. Even to this sin men are now tempted, when drawn aside by their own lusts and fancies. Such men are roots that bear gall and wormwood. They are weeds which, if let alone, overspread the whole field. Satan may for a time disguise this bitter morsel, so that thou shalt not have the natural taste of it, but at the last day, if not before, the true taste shall be discerned. Notice the sinner's security in sin. Though he hears the words of the curse, yet even then he thinks himself safe from the wrath of God. There is scarcely a threatening in all the book of God more dreadful than this. Oh that presumptuous sinners would read it, and tremble! for it is a real declaration of the wrath of God, against ungodliness and unrighteousness of man.