a ambos lados
From LSJ
ὀφθαλμοὶ γὰρ τῶν ὤτων ἀκριβέστεροι μάρτυρες → the eyes are more accurate witnesses than the ears, the eyes are more exact witnesses than the ears
Spanish > Greek
ἑκατέρωθεν, ἀμφί, ἀμφοτέρωθεν, ἀμφοτέρωθε, δεξιοαριστερός, ἔνθεν