O Clavis David
Continuing on, we come closer and closer to the birth of the Messiah, “the holy one, the true, who holds the key of David, who opens and no one shall close, who closes and no one shall open” (Rev. 3:7).
If you are interested in learning more about the O Antiphons, I recommend Fr. Zuhlsdorf’s site here. The format is bare-bones, but the information is thorough.
O Clavis David, et sceptrum domus Israël;
qui áperis, et nemo claudit;
claudis, et nemo áperit:
veni, et educ vinctum de domo cárceris,
sedéntem in ténebris, et umbra mortis.
Englished:
O Key of David and sceptre of the House of Israel;
you open and no one can shut;
you shut and no one can open:
Come and lead the prisoners from the prison house,
those who dwell in darkness and the shadow of death.