I am making this covenant and this oath not only with you,
It appears by the length of the sentences here, and by the copiousness and pungency of the expressions, that Moses, now that he was drawing near to the close of his discourse, was very warm and zealous, and very desirous to impress what he said upon the minds of this unthinking people.
Commenting on Deuteronomy 29:10-29
Neither with you only do I make this covenant and this oath. That is, Moses; for he was ordered to make this covenant with them in the name of the Lord; what promises of good things, or declarations of his mind and will, God would make, Moses was to deliver to them; and what was required of them he would inform them of.
Deu 29:14-15 This covenant Moses made not only with those who are present, but with all whether present or not; for it was to embrace not only those who were living then, but their descendants also, to become a covenant of blessing for all nations (cf. Act 2:39, and the intercession of Christ in Joh 17:20).
Commenting on Deuteronomy 29:14-15