O Sacred Lord

 The Great Antiphons are responses to the praying of the Magnificat in the Vespers service, during the last week of Advent.  So, to put the antiphon more properly in its liturgical context:

My soul extols the Lord, and my spirit rejoices in God my Savior, for he has shown consideration for the lowly stature of his slave. As a consequence, from now on every generation will congratulate me; the Mighty One has done great things for me, and holy is his name, and his mercy will come to generation after generation of those who fear him. He has shown the strength of his arm, he has put the arrogant to rout, along with their private schemes; he has pulled the mighty down from their thrones, and exalted the lowly; he has filled the hungry with good things, and sent the rich away empty. He has come to the aid of his servant Israel, remembering his mercy, as he spoke to our ancestors, to Abraham and to his descendants forever. (Luke 1:46-56, SV)

O sacred Lord of ancient Israel, who showed yourself to Moses in the burning bush, who gave him the holy law on Sinai mountain: Come, stretch out your mighty hand to set us free.

18 Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost.

19 Then Joseph her husband, being a just man, and not willing to make her a public example, was minded to put her away privily.

20 But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost.

21 And she shall bring forth a son, and thou shalt call his name Jesus: for he shall save his people from their sins.

22 Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying,

23 Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.

--Matthew 1:18-23, KJV