σούσθω

From LSJ

ὁ δ' εὖ ἔρδων θεοὺς ἐλπίδι κυδροτέρᾳ σαίνει κέαρ → but he who does well to the gods cheers his heart with a more glorious hope

Source

French (Bailly abrégé)

3ᵉ sg. impér. prés. Moy. de σοῦμαι, c. σεύομαι, v. σεύω.