O God, who in the glorious Transfiguration of your Only Begotten Son confirmed the mysteries of faith by the witness of the Fathers and wonderfully prefigured our full adoption to sonship, grant, we pray, to your servants, that, listening to the voice of your beloved Son, we may merit to become co-heirs with him. Who lives and reigns with you in the unity of the Holy Spirit, one God, for ever and ever. Amen
Courtesy of here. Today is the Feast of the Transfiguration.