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

[spiros]

ἡ κέρκος τῇ ἀλώπεκι μαρτυρεῖ → small traits give the clue to the character of a person
cauda de vulpe testificatur, ex pede Herculem

Gli asini si conoscono a' basti, cioè Le qualità d'uno si conoscono dall'esterno. Lat. cauda de vulpe testatur. Gr. ἡ κέρκος τῇ ἀλώπεκι μαρτυρεῖ.
http://www.lessicografia.it/Controller?lemma=ASINO&rewrite=1

el rabo delata a la zorra e.d. se le ve a uno el plumero (las intenciones)
ἀλώπηξ - Ancient Greek (LSJ)

εξ όνυχος τον λέοντα → small traits give the clue to the character of a person, deduce something from a small indication, judge from the details