The third of the O Antiphons.

O Radix Jesse,
qui stas in signum populorum,
super quem continebunt reges os suum,
quem gentes deprecabuntur:
veni ad liberandum nos,
iam noli tardare

In English:

O Root of Jesse,
Who stands as a sign for the people,
Before whom kings shall keep silence,
Whom the nations will worship:
Come to set us free,
Put it off no longer.