μηδενί δίκην δικάσῃς πρίν ἀμφοῖν μῦθον ἀκούσῃς → do not give your judgement on anything until you have heard a speech on both sides
τρισκαιδεκέτης: -ου, ὁ, ὁ ἔχων ἡλικίαν δεκατριῶν ἐτῶν, Λυσί. 116. 28.