The Lord [is] thy keeper
This explains more fully who it is that keeps Israel and particular believers, and confirms the same; not a creature, but the Lord; the Word of the Lord, as the Targum, in ( Psalms 121:7 ) : Christ, the Word and Wisdom of God; who is the keeper of his people by the designation of his Father, who has put them into his hands to be kept by him; and by their full will and consent, who commit the keeping of their souls to him; for which he is abundantly qualified, being able as the mighty God; faithful to him that has appointed him; tender and compassionate to those under his care, whom he keeps as the apple of his eye; and diligent and constant, for he keeps them night and day, lest any hurt them: he keeps them as they are his flock, made his care and charge; as they are the vineyard of the Lord of hosts; as they are a city, which, unless the Lord keeps, the watchmen watch in vain; as they are his body and members of it, and as they are his jewels and peculiar treasure: these he keeps in the love of God; in his own hands; in the covenant of grace; in an estate of grace; and in his own ways, safe to his kingdom and glory;
the Lord [is] thy shade upon thy right hand;
he is at the right hand of his people, to hold their right hand; to teach them to go, lead them into communion with himself, and hold them up safe; and to strengthen their right hand, assist them in working, without whom they can do nothing; and to counsel and direct them, and to protect and defend them against all their enemies. So a shadow signifies defence; see ( Numbers 14:9 ) ( Ecclesiastes 7:12 ) ; and such great personages are to others; in which sense Virgil F14 uses the word "shadow"; and much more true is this of God himself. And he is like the shadow of a great rock in a weary land; or of a spreading tree, which is a protection from heat, and very reviving and refreshing; see ( Isaiah 32:2 ) ( Song of Solomon 2:3 ) . The allusion may be to the pillar of cloud by day, which guided and guarded the Israelites in the wilderness, and was a shadow from the heat, ( Isaiah 4:5 Isaiah 4:6 ) ( Isaiah 25:4 Isaiah 25:5 ) ; as Christ is from the heat of a fiery law, the flaming sword of justice, the wrath of God, and the fiery darts of Satan.