That join themselves to the Lord - Who shall enter into the Christian covenant by baptism and faith in Christ, as the Jews and proselytes did by circumcision.
To serve him - To live according to the Gospel, and ever do that which is right in the sight of the Lord.
To love the name of the Lord - The name of Jesus, the Christ, the Savior of sinners, the Anointed of God, and the Giver of the Holy Spirit to his followers.
To be his servants - To worship no other God but Jehovah, and to trust in none for salvation but his Christ.
That keepeth the Sabbath - That observes it as a type of the rest that remains for the people of God.
And taketh hold of my covenant - בבריתי biberithi, “of my covenant sacrifice;” as without this he can do nothing good; and without it nothing can be acceptable to the infinite majesty of the Most High.