In the sixth month, the angel Gabriel was sent from God to a town of Galilee called Nazareth,
to a virgin betrothed to a man named Joseph, of the house of David, and the virgin's name was Mary.
And coming to her, he said, "Hail, full of grace! The Lord is with you."
But she was greatly troubled at what was said and pondered what sort of greeting this might be.
Then the angel said to her, "Do not be afraid, Mary, for you have found favor with God.
Behold, you will conceive in your womb and bear a son, and you shall name him Jesus.
He will be great and will be called Son of the Most High, and the Lord God will give him the throne of David his father,
and he will rule over the house of Jacob forever, and of his kingdom there will be no end."
But Mary said to the angel, "How can this be, since I have no relations with a man?"
And the angel said to her in reply, "The Holy Spirit will come upon you, and the power of the Most High will overshadow you. Therefore the child to be born will be called holy, the Son of God.
And behold, Elizabeth, your relative, has also conceived a son in her old age, and this is the sixth month for her who was called barren;
for nothing will be impossible for God."
Mary said, "Behold, I am the handmaid of the Lord. May it be done to me according to your word." Then the angel departed from her.

Gospel commentary

Saint Bede the Venerable (c.673-735), monk, Doctor of the Church
Homilies for Advent, no. 3 ; CCL 122, 14-17 (Christ our Light, pub. Exordium books, 1981, ©Friends of Henry Ashworth, pp. 32-33)

“The angel Gabriel was sent from God to a city of Galilee named Nazareth, to a virgin betrothed to a man whose name was Joseph of the house of David; and the virgin's name was Mary.” What is said of the house of David applies not only to Joseph but also to Mary. It was a precept of the law that each man should marry a wife from his own tribe and kindred. Saint Paul also bears testimony to this when he writes to Timothy: “Remember Jesus Christ, risen from the dead, descended from David, as preached in my Gospel” (2 Tm 2:8) (…)

“He will be great, and will be called the son of the Most High; and the Lord God will give him the throne of his father David.” The angel refers to the kingdom of the Israelite nation as the throne of David because in his time, by the Lord's command and assistance, David governed it with a spirit of faithful service (…) As David had once ruled the people with temporal authority, so Christ would now lead them to the eternal kingdom by his spiritual grace (…)

“He will reign over the house of Jacob for ever”. The house of Jacob here refers to the universal Church which, through its faith in and witness to Christ, shares the heritage of the patriarchs. This may apply either to those who are physical descendants of the patriarchal families, or to those who come from gentile nations and are reborn in Christ by the waters of baptism. In this house Christ shall reign for ever, and “of his kingdom there will be no end”. During this present life, Christ rules in the Church. By faith and love he dwells in the hearts of his elect, and guides them by his unceasing care toward their heavenly reward. In the life to come, when their period of exile on earth is ended, he will exercise his kingship by leading the faithful to their heavenly country. There, for ever inspired by the vision of his presence, their one delight will be to praise and glorify him.