ὅρκῳ ζευγνύναι

From LSJ

ἐὰν ἃ τοῖς ἄλλοις ἐπιτιμῶμεν, αὐτοὶ μὴ δρῶμεν → avoid doing what you would blame others for doing

Source

Greek > English (Woodhouse)

bind by an oath