O KEY OF DAVID and Scepter of the house of Israel: You open, and no man closes; You close, and no man opens. COME,and deliver him from the chains of prison who sits in darkness and in the shadow of death!
The following commentary adapted from The Church’s Year of Grace, Fr Pius Parsch (The Liturgical Press, Collegeville, 1959):
Substantially, this passage is from Revelation 3:7, where Christ speaks of Himself as the “Key of David who opens and no one shuts; who shuts and no one opens.” But there is also a passage in Isaiah (22:22) which corresponds almost word-for-word with our antiphon. There the text is directed to the faithful civil ruler whom God supports: “I will lay the key of the house of David upon his shoulder. He will open and no one will shut; he will shut, and no one will open.” The symbol of handing over the keys denotes the conferral of supreme authority. Evidently St. John borrowed the passage from Isaiah and applied it to Christ, a precedent followed by the liturgy.
Being the son of David, Christ is heir and possessor of David’s keys (i.e., his kingdom). After His resurrection, He told His apostles, “All power is given to Me in heaven and on earth.” Lastly, the petition of this antiphon is somewhat more extended than on previous days. Christ holds the keys to the prison where humanity is enchained. Redemption is described graphically in this antiphon—captive mankind sits in darkness and in the black shadows of death. May Christ the Redeemer, we plead, come and unlock this prison.