ἀποκριτέον
From LSJ
Τὸ νικᾶν αὐτὸν αὑτὸν πασῶν νικῶν πρώτη τε καὶ ἀρίστη. Τὸ δὲ ἡττᾶσθαι αὐτὸν ὑφ' ἑαυτοῦ πάντων αἴσχιστόν τε ἅμα καὶ κάκιστον. → Τo conquer yourself is the first and best victory of all, while to be conquered by yourself is of all the most shameful as well as evil
English (LSJ)
A one must reject, opp. ἐγκριτέον, Pl.R.377c, 413d, cf. Lib.Or.25.53. II one must answer, Pl.Prt.351d, Alc.1.114e, etc.