These words of the Lord by the prophet Malachi (3:1ff) speak of the Lord's sending of His Angel to His Temple. When it was time for Mary's purification, Jesus' parents brought Jesus to the Temple and presented Him there (Luke 2:22-32).
Jesus would be the sacrifice pleasing to the Lord. On this day the Nunc Dimíttis is emphasized, it is found in the Gospel, Antiphon, etc.:
Now Thou dost dismiss Thy Servant, O Lord,
according to Thy word in peace;
because mine eyes have seen Thy salvation,
which Thou hast prepared before the face of all peoples . . .
Among those receiving the blessed Eucharist these words are a fitting echo for we have seen and received the Lord's salvation. He, born of the Blessed Virgin, purifies us of our sins.