ὁμοψύχως

From LSJ

οὐ γὰρ ἂν τό γε πραχθὲν ἀγένητον θείη → since he cannot make what was done as though it had not come to pass

Source

Greek (Liddell-Scott)

ὁμοψύχως: Ἐπίρρ., μιᾷ ψυχῇ καὶ μιᾷ γνώμῃ, ὁμοθυμαδόν, μεταγεν.