Isaiah 60:21 - Matthew Poole's English Annotations on the Holy Bible

Thy people also shall be all righteous, i.e. the greater part; the word in this use hath been shown frequently; or, altogether righteous, completely righteous. As this respects the Jews, the sense may be, they went into captivity wicked, but most of them being dead, and many of the survivors tarrying behind, they that are returned are said to be righteous, Isaiah 1:25-27 4:4: but principally as it respects the church, they shall be all saints, either by profession, as Paul calls them frequently saints by calling; or rather by an inherent righteousness, or perfectly by the imputed righteousness of Christ: See Poole on "Isaiah 35:8". They shall inherit the land for ever, i.e. for a long time, as you have many instances; and this is spoken, lest that poor remnant should be afraid of being driven out again; but with reference to the church, that they should for ever be continued as God's peculiar people. The branch of my planting; put by apposition, viz. Thy people being of my planting, and so also the next clause, the work of my hands, and therefore cannot miscarry, being what I shall take delight in; and thus the children of God are said to be his workmanship, created in Christ Jesus, Ephesians 2:10. That I may be glorified; either that I may make them glorious in being thus planted, or myself glorious in thus planting them.