For he established a testimony in Jacob - He ordained or appointed that which would be for a “witness” for him; that which would bear testimony to his character and perfections; that which would serve to remind them of what he was, and of his authority over them. Any law or ordinance of God is thus a standing and permanent witness in regard to his character as showing what he is.
And appointed a law in Israel - That is, He gave law to Israel, or to the Hebrew people. Their laws were not human enactments, but were the appointments of God.
Which he commanded our fathers ... - He made it a law of the land that these testimonies should be preserved and faithfully transmitted to future times. See Deuteronomy 4:9; Deuteronomy 6:7; Deuteronomy 11:19. They were not given for themselves only, but for the benefit of distant generations also.