The Worship of the Trinity Was Made Manifest
When Thou wast baptized in the Jordan, O Lord, the worship of the Trinity was made manifest! For the voice of the Father bare witness to Thee, calling Thee his Beloved Son. And the Spirit, in the form of a dove, confirmed the truthfulness of his Word. O Christ our God, who hast revealed Thyself and hast enlightened the world, glory to Thee! ~Troparion of the Feast of the Theophany of Christ
Today Thou hast appeared to the universe, end Thy Light, O Lord, has shone on us, who with understanding praise Thee: Thou hast come and revealed Thyself, O Light Unapproachable! ~Kontakion of the Feast
Then cometh Jesus from Galilee to Jordan unto John, to be baptized of Him. But John forbad Him, saying, I have need to be baptized of thee, and comest thou to me? And Jesus answering said unto him, Suffer it to be so now: for thus it becometh us to fulfill all righteousness. Then he suffered him. And Jesus, when He was baptized, went up straightway out of the water: and, lo, the heavens were opened unto Him, and He saw the Spirit of God descending like a dove, and lighting upon Him: And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased. ~The Gospel according to St. Matthew 3:13-17
Via Orthodox Christian.