доверие

From LSJ

κέρκος τῇ ἀλώπεκι μαρτυρεῖ → you can tell a fox by its tail, small traits give the clue to the character of a person

Source

Russian > Greek

πιστόν, πίστις, πεποίθησις, θάρσησις, εὐπιστία, πεῖσμα