13 to confirm you this day as his people, that he may be your God as he promised you and as he swore to your fathers, Abraham, Isaac and Jacob.

Read Deuteronomy 29:13 Using Other Translations

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.
that he may establish you today as his people, and that he may be your God, as he promised you, and as he swore to your fathers, to Abraham, to Isaac, and to Jacob.
By entering into the covenant today, he will establish you as his people and confirm that he is your God, just as he promised you and as he swore to your ancestors Abraham, Isaac, and Jacob.