Latin: O clavis David, et sceptrum domus Israel: qui aperis, et nemo claudit; claudis, et nemo aperit: veni, et educ vinctum de domo carceris, sedentem in tenebris.
English: O Key of David, and scepter of the house of Israel, who opens and no man shuts, who shuts and no man opens; come, and bring forth the captive from his prison, he who sits in darkness and in the shadow of death.
Relevant verse of Veni, Veni Emmanuel:
O come, thou Key of David, come, And open wide our heavenly home;
Make safe the way that leads on high; and close the path to misery.