Phos Hilaron (Greek: Φῶς ἱλαρὸν; Slavonic:Све́те ти́хий ) is an ancient Christian hymn originally written in Koine Greek. The hymn is known in English as ‘O Gladsome Light.’ It is the earliest known Christian hymn, recorded outside of the Bible, that is still being used today. The hymn is sung at Vespers in the Orthodox Catholic Church.
O Gladsome Light of the holy glory of the Immortal Father, heavenly, holy, blessed Jesus Christ. Now we have come to the setting of the sun and behold the light of evening. We praise God: Father, Son, and Holy Spirit. For it is right at all times to worship Thee with voices of praise, O Son of God and Giver of Life, therefore all the world glorifies Thee.
Φῶς ἱλαρὸν ἁγίας δόξης, ἀθανάτου Πατρός, οὐρανίου, ἁγίου, μάκαρος, Ἰησοῦ Χριστέ, ἐλθόντες ἐπὶ τὴν ἡλίου δύσιν, ἰδόντες φῶς ἑσπερινόν, ὑμνοῦμεν Πατέρα, Υἱόν, καὶ ἅγιον Πνεῦμα Θεόν. Ἄξιόν σε ἐν πᾶσι καιροῖς, ὑμνεῖσθαι φωναῖς αἰσίαις, Υἱὲ Θεοῦ, ζωὴν ὁ διδούς, Διὸ ὁ κόσμος σὲ δοξάζει.