According to the Sarum use, at today's Mass of Christmas Eve, before the epistle, the following prophecy is sung by a single acolyte, standing at the choir step (i.e. the step between the choir and what would be the sanctuary in modern churches), wearing just a simple alb:

Propter Sion non tacebo et propter Hierusalem non quiescam donec egrediatur ut splendor iustus eius et salvator eius ut lampas accendatur. Et videbunt gentes iustum tuum et cuncti reges inclitum tuum et vocabitur tibi nomen novum quod os Domini nominabit. Et eris corona gloriae in manu Domini et diadema regni in manu Dei tui. Non vocaberis ultra Derelicta et terra tua non vocabitur amplius Desolata sed vocaberis Voluntas mea in ea et terra tua Inhabitata quia conplacuit Domino in te. 

For Sion's sake I will not hold my peace, and for the sake of Jerusalem, I will not rest till her just one come forth as brightness, and her saviour be lighted as a lamp. And the Gentiles shall see thy just one, and all kings thy glorious one: and thou shalt be called by a new name, which the mouth of the Lord shall name. And thou shalt be a crown of glory in the hand of the Lord, and a royal diadem in the hand of thy God. Thou shalt no more be called Forsaken: and thy land shall no more be called Desolate: but thou shalt be called My pleasure in her, and thy land inhabited. Because the Lord hath been well pleased with thee.