Plato, Euthyphro 10a

“Is something loved by the gods because it is holy or holy because it is loved?”

ἆρα τὸ ὅσιον ὅτι ὅσιόν ἐστιν φιλεῖται ὑπὸ τῶν θεῶν, ἢ ὅτι φιλεῖται ὅσιόν ἐστιν

Yeah, this line gets its own Wikipedia page.

Here’s the full text.