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.
If it looks like Greek, it is. This is one of the oldest post-Biblical texts still sung today. If I were crafting a parish repertoire for the Liturgy of the Hours, this would have to be the first non-Scriptural text included. It has a steady history in Eastern Christianity. It may be familiar to readers in this translation/adaptation by William Storey:
O radiant light, O sun divine
Of God the Father’s deathless face,
O image of the light sublime
That fills the heav’nly dwelling place.
O Son of God, the source of life,
Praise is your due by night and day;
Our happy lips must raise the strain
Of your esteemed and splendid name.
Lord Jesus Christ, as daylight fades,
As shine the lights of eventide,
We praise the Father with the Son,
The Spirit blest and with them one.
This text became familiar to me in the 80s as I experienced Evening Prayer from the GIA collection Praise God in Song. My first exposure to it was with a Michael Joncas musical setting, but the most common usage in my experience over the past forty years is with various settings to the tune Jesu Dulcis Memoria. The text and this tune are so wedded in my ears that any other use of either seems jarring to me.
Alert eyes might notice the invocation of the Trinity (Πατέρα, Υἱόν, καὶ ἅγιον Πνεῦμα) in line 4 of the Greek original, not the conclusion. Perhaps readers more familiar with Orthodox hymnody might comment on the placement of this in Orthodox liturgical texts.