λανθάνειν ποιῶν τι
From LSJ
Κακοῦ μεταβολὴν ἀνδρὸς οὐ δεῖ προσδοκᾶν → Non exspectandus improbi flexus viri → Auf Wandel eines schlechten Mannes warte nicht
Greek > English (Woodhouse)
do a thing imperceptibly, do a thing inadvertantly, do a thing unconsciously, do a thing unobserved, do a thing unperceived, do a thing unseen, do a thing unwittingly