Matthew 7:15

Προσέχετε δέ ἀπὸ τῶν ψευδοπροφητῶν, οἵτινες ἔρχονται πρὸς ὑμᾶς ἐν ἐνδύμασι προβάτων, ἔσωθεν δὲ εἰσι λύκοι ἅρπαγες.

And beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves.