οἰκεῖος ἀνθρώποισι γίγνεσθαι φιλεῖ πόλεμος ἐν ἀστοῖς ἢν διχοστατῇ πόλις

From LSJ

μηδενί δίκην δικάσῃς πρίν ἀμφοῖν μῦθον ἀκούσῃς → do not give your judgement on anything until you have heard a speech on both sides

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