The O Antiphons have been prayed at evening prayer starting December 17th until Christmas Eve since at least the 4th century. Each one focuses on a different biblical name for Our Lord, and are a great way to pray and reflect on many of the ramifications of the Incarnation of God in Bethlehem over 2000 years ago.
December 17th: O Sapientia (O Wisdom)
You came forth from the mouth of the Most High (Sirach 24:3),
and reaching from beginning to end You ordered all things mightily and sweetly (Wisdom 8:1).
Come, and teach us the way of prudence (Isaiah 40:14).
December 18th: O Adonai (O Lord)
O Lord (Exodus 3:14)
and Ruler of the house of Israel (Matthew 2:6; Micah 5:1),
You appeared to Moses in the fire of the burning bush (Exodus 3:2)
and on Mount Sinai gave him Your Law (Exodus 20).
Come, and with an outstretched arm redeem us (Jeremiah 32:21).
December 19th: O Radix Jesse (O Root of Jesse)
O Root of Jesse, (Isaiah 11:1)
You stand for the ensign of mankind (Isaiah 11:10); before You kings shall keep silence and to You all nations shall have recourse (Isaiah 52:15).
Come, save us, and do not delay (Habakkuk 2:3).
December 20th: O Clavis David (O Key of David)
O Key of David, (Isaiah 22:22; Revelation 3:7)
and Scepter of the house of Israel (Numbers 24:17):
You open and no man closes; you close and no man opens (Isaiah 22:22).
Come, and deliver him from the chains of prison who sits in darkness and in the shadow of death (Ps 107:10).
December 21st: O Oriens (O Dayspring)
O Dayspring, (Hebrews 1:3),
Radiance of the Light eternal (Habakkuk 3:4; Wisdom 7:26)
and Sun of Justice (Malachi 3:20):
come, and enlighten those who sit in darkness and in the shadow of death (Psalms 107:10; Luke 1:78).
December 22nd: O Rex Gentium (O King of All The Nations)
O King of the All Nations (Jeremiah 10:7; Haggai 2:7),
and the Desired of all,
You are the Cornerstone that binds two into one (Isaiah 28:16; Matthew 21:42; Ephesians 2:20).
Come, and save man whom You fashioned out of clay (Genesis 2:7).
December 23rd: O Emmanuel (O God With Us)
O Emmanuel (Isaiah 7:14; 8:8; Luke 1:31-33),
our King and Lawgiver (Genesis 49:10; Ezekiel 21:32),
the Expected of the nations and their Savior (Isaiah 33:22):
Come, and save us, O Lord our God.