ἕξις σφαλερὰ πρὸς ὑγίειαν

From LSJ

τὸ δὲ ποιεῖν ἄνευ νοῦ ἃ δοκεῖ καὶ σὺ ὁμολογεῖς κακὸν εἶναι: ἢ οὔ → but doing what one thinks fit without intelligence is—as you yourself admit, do you not?—an evil

Source

Dutch (Woordenboekgrieks.nl)

gevaarlijk voor de gezondheid

Russian (Dvoretsky)

шаткое здоровье