Deuteronomy 29:1

Now that Moses had largely repeated the commands which the people were to observe as their part of the covenant, and the promises and threatenings which God would make good (according as they behaved themselves) as part of the covenant, the whole is here summed up in a federal transaction. The covenant formerly made is here renewed, and Moses, who was before, is still, the mediator of it (Deu 29:1): The Lord commanded Moses to make it. Moses himself, though king in Jeshurun, could not make the covenant any otherwise than as God gave him instructions. It does not lie in the power of ministers to fix the terms of the covenant; they are only to dispense the seals of it. This is said to be besides the covenant made in Horeb; for, though the covenant was the same, yet it was a new promulgation and ratification of it. It is probable that some now living, though not of age to be mustered, were of age to consent for themselves to the covenant made at Horeb, and yet it is here renewed. Note, Those that have solemnly covenanted with God should take all opportunities to do it again, as those that like their choice too well to change. But the far greater part were a new generation, and therefore the covenant must be made afresh with them, for it is fit that the covenant should be renewed to the children of the covenant. I.

— Matthew Henry's Concise Commentary (public domain)