ἀμυνάθω
From LSJ
μὴ κακὸν εὖ ἔρξῃς· σπείρειν ἴσον ἔστ' ἐνὶ πόντῳ → do no good to a bad man; it is like sowing in the sea
English (LSJ)
pres. assumed by Gramm., cf. Hdn.Gr.1.440, 2.782, as lengthd. form of ἀμύνω: but forms so accented in codd. are best taken to belong to aor. ἠμύναθον and written ἀμυναθεῖν (so Hsch.), -θοῦ, cf. ἀλκαθεῖν:—
A defend, assist, c. dat. pers., εἰ σοῖς φίλοις ἀμυναθεῖν χρῄζεις E.Andr.1079, cf. IA910; ἀμυνάθετέ μοι Ar.Nu.1323: abs., ἄξιαι δ' ἀμυναθεῖν [αἱ ξυμφοραί] S.OC1015:—Med., ward off from oneself, repel, τόνδ' ἀμυναθοῦ ψόγον A.Eu.438; take vengeance on, μὴ . . ἀμυνάθοιτό σε E.Andr.721.