This holiday was established in memory of the glorious transfiguration of Jesus Christ before the disciples on Mount Tabor, to show them His Divine greatness and strengthen their faith on the occasion of His approaching suffering. The evangelists tell almost the same story about this event: Matthew, ch. 17, art. 1-8 (Matt. 17:1-8); Mark, ch. 9, art. 2-8 (Mark 9:2-8); Luke, ch. 9, art. 28-36 (Luke 9:28-36).
According to the Gospel of Matthew:
After six days had passed (after the prediction of Jesus Christ about His suffering on the cross, death and resurrection), Jesus took Peter, James and John his brother, and led them up a high mountain alone. And He was transfigured before them: and His face shone like the sun, and His clothes became white as light. And behold, Moses and Elijah appeared to them, talking with Him. At this Peter said to Jesus: Lord! It’s good for us to be here; If you want, we will make three tabernacles here: one for you, one for Moses, and one for Elijah. While he was still speaking, behold, a bright cloud overshadowed them, and behold, a voice from the cloud, saying: This is my beloved Son, in whom I am well pleased; Listen to him. And when the disciples heard, they fell on their faces and were very afraid. But Jesus came and touched them and said: Arise and do not be afraid. Lifting up their eyes, they saw no one except Jesus alone.
Troparion.
Thou art transfigured on the mountain, O Christ God, showing Thy disciples Thy glory, as unto a man: may Thy ever-present light shine upon us sinners also, through the prayers of the Theotokos. Light giver, glory to You.
Kontakion.
You were transfigured on the mountain, and as the host of Your disciples, You saw Your glory, O Christ God: that when they see You crucified, they will understand free suffering, and they will preach to the world that You are truly the Father’s radiance.
Greatness.
We magnify You, life-giving Christ, and honor Your most pure flesh and glorious transfiguration.
Zadostoynik.
Magnify, my soul, the Lord who was transfigured on Tabor.
9. Thy Nativity appeared incorruptibly: God passed from Thy side, like a flesh-bearer appearing on earth, and living with men. Thee, Mother of God, is why we magnify everything.