C. F. Keil and Franz Delitzsch on Isaiah 60:21

Isa 60:21

The next v. shows how deep was his consciousness of the close connection between darkness, wrath, and sin. “And thy people, they are all righteous; they possess the land for ever, a sprout of my plantations, a work of my hands for glorification.” The church of the new Jerusalem consists of none but righteous ones, who have been cleansed from guilt, and keep themselves henceforth pure from sinning, and therefore possess the land of promise for ever, without having to fear repeated destruction and banishment: a “sprout” (nētser as in Isa 11:1; Isa 14:19; Arab. nadr, the green branch) “of my plantations” (מטּעי chethib, erroneously מטּעו or מטּעו), i.e., of my creative acts of grace (cf., Isa 5:7), a “work of my hands” (cf., Isa 19:25), “to glorify me,” i.e., in which I possess that in which I glory (להתפּאר as in Isa 61:3).