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.” (Lk 1:26-38)
https://bible.usccb.org/bible/readings/040824.cfm
Normally, the Annunciation is celebrated on March 25. But this year, due to Holy Week and the Octave of Easter, today is the first day “free” to celebrate his coming into the world to accomplish the great work of our salvation. And in the middle of this solemn announcement to the Virgin Mary, the excited angel breaks into the Hallelujah Chorus!