περιορᾶν τινὰ ἀδικούμενον

From LSJ

ἀπορράπτειν τὸ Φιλίππου στόμα ὁλοσχοίνῳ ἀβρόχῳ → sew up Philip's mouth with an unsoaked rush, stop Philip's mouth with an unsoaked rush, shut one's mouth without any trouble

Source

Greek > English (Woodhouse)

stand by and see a person injured