Today's O Antiphon:
“O Key of David, O royal Power of Israel controlling at your will the gate of Heaven: Come, break down the prison walls of death for those who dwell in darkness and the shadow of death; and lead your captive people into freedom.” Isaiah had prophesied, I will place the Key of the House of David on His shoulder; when he opens, no one will shut, when he shuts, no one will open.” (Isaiah 22:22), and “His dominion is vast and forever peaceful, from David’s throne, and over His kingdom, which he confirms and sustains by judgment and justice, both now and forever.” (9:6).
Jesus fulfills and reflects Isaiah's prophesy by giving Peter "the keys to the kingdom of heaven. What you bind on earth shall be bound in Heaven. Whatever you loose on earth shall be loosed in Heaven." (Matthew 16:19)