John Gill Commentary Deuteronomy 10:21

"He is thy praise, and he is thy God, that hath done for thee these great and terrible things, which thine eyes have seen." — Deuteronomy 10:21 (ASV)

He is your praise
The object and matter of it, who deserves the praises of all his creatures, because of his perfections, works, and blessings of goodness; for all mercies temporal and spiritual come from him, and therefore he is greatly to be praised for them: praise is his due, and it is comely in his people to give it to him; see (Jeremiah 17:14)

and he is your God which has done for you these great and terrible
things which your eyes have seen ;
which were done upon the Egyptians for their sakes, both in the land of Egypt and at the Red sea; and also what he had done for them in the wilderness, to Sihon and Og, kings of the Amorites, (Psalms 106:22) (136:10-21) .