Radak

Of Thee is my praise: – The speaker is every individual Israelite, or else all Israel as one, inasmuch as they are the subject of the Psalm: my praise, i.e. with which I praise Thee: in the great congregation – of the nations; it (my praise) is of Thee, for Thou hast been to me the occasion of praise because Thou didst deliver me. My vows – which I vowed – will I pay before them that fear Him: – for all the nations will fear Him then, as he says (infra): All the ends of the earth shall remember and turn unto the Lord.