This year The Vigil of the Nativity of Our Lord (Christmas Eve) falls on the Fourth Sunday of Advent. Since these two days concur, the historic rubrics direct that the Mass of Christmas Eve is celebrated and Sunday is commemorated by adding the Collect for Advent IV after the Collect for Christmas Eve.
Roman and Anglican sources provide the following:
This Mass is celebrated in Violet vestments and the Gloria in Excelsis is not sung.
Introit: Exodus 16. Psalm 24.
Today you shall know that the Lord will come and deliver you: and in the morning you shall see the glory of the Lord. Ps. The earth is the Lord's, and the fulness thereof; the world, and they that dwell therein. Glory be to the Father....
Collect: (From TLH, Other Collects for the Season of Advent)
O God, who dost gladden us with the early (yearly) anticipation of our redemption, grant that we who now joyfully receive Thine only-begotten Son as our Redeemer may also behold Him without fear when He cometh as our Judge; who liveth, etc.
The Collect for Advent IV is then said to commemorate the Sunday.
Epistle: Romans 1:1-6
Gradual: (Exodus 16)
Today ye shall know that the Lord will come and deliver you: and in the morning ye shall see the glory of the Lord. Ps. 80 Give ear, O Shepherd of Israel: Thou that leadest Joseph like a flock: thou that dwellest between the cherubim, shine forth before Ephraim and Benjamin and Manasseh.
Alleluia, alleluia. Tomorrow the iniquity of the earth shall be done away: and the Savior of the world shall reign over us. Alleluia.
Gospel: St. Matthew 1:18-21
Lamentably, Lutheran service books do not include propers for a Mass on Christmas Eve. Even the listings of Epistles and Gospels for Sundays and various Feasts found in early twentieth century German Bibles do not include Christmas Eve. I do not know if the LSB has corrected this omission.