Be on your guard against false prophets; they come to you looking like sheep on the outside, but on the inside they are really like wild wolves. You will know them by what they do. Thorn bushes do not bear grapes, and briers do not bear figs. A healthy tree bears good fruit, but a poor tree bears bad fruit. A healthy tree cannot bear bad fruit, and a poor tree cannot bear good fruit. And any tree that does not bear good fruit is cut down and thrown in the fire. So then, you will know the false prophets by what they do.

[Προσέχετε ἀπὸ τῶν ψευδοπροφητῶν, οἵτινες ἔρχονται πρὸς ὑμᾶς ἐν ἐνδύμασιν προβάτων, ἔσωθεν δέ εἰσιν λύκοι ἅρπαγες. ἀπὸ τῶν καρπῶν αὐτῶν ἐπιγνώσεσθε αὐτούς. μήτι συλλέγουσιν ἀπὸ ἀκανθῶν σταφυλὰς ἢ ἀπὸ τριβόλων σῦκα; οὕτως πᾶν δένδρον ἀγαθὸν καρποὺς καλοὺς ποιεῖ, τὸ δὲ σαπρὸν δένδρον καρποὺς πονηροὺς ποιεῖ. οὐ δύναται δένδρον ἀγαθὸν καρποὺς πονηροὺς ποιεῖν οὐδὲ δένδρον σαπρὸν καρποὺς καλοὺς ποιεῖν. πᾶν δένδρον μὴ ποιοῦν καρπὸν καλὸν ἐκκόπτεται καὶ εἰς πῦρ βάλλεται. ἄρα γε ἀπὸ τῶν καρπῶν αὐτῶν ἐπιγνώσεσθε αὐτούς.]

The Bible (The New Testament) (AD 1st - 2nd C) Christian sacred scripture

Matthew 7:15-20 (Jesus) [GNT (1976)]
    (Source)

The fruit/tree part of the passage is paralleled in Luke 6:43-44, and echoed in Matthew 12:33.

(Source (Greek)). Alternate translations:

Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them.
[KJV (1611)]

Beware of false prophets who come to you disguised as sheep but underneath are ravenous wolves. You will be able to tell them by their fruits. Can people pick grapes from thorns, or figs from thistles? In the same way, a sound tree produces good fruit but a rotten tree bad fruit. A sound tree cannot bear bad fruit, nor a rotten tree bear good fruit. Any tree that does not produce good fruit is cut down and thrown on the fire. I repeat, you will be able to tell them by their fruits.
[JB (1966)]

Beware of false prophets who come to you disguised as sheep but underneath are ravenous wolves. You will be able to tell them by their fruits. Can people pick grapes from thorns, or figs from thistles? In the same way, a sound tree produces good fruit but a rotten tree bad fruit. A sound tree cannot bear bad fruit, nor a rotten tree bear good fruit. Any tree that does not produce good fruit is cut down and thrown on the fire. I repeat, you will be able to tell them by their fruits.
[NJB (1985)]

Watch out for false prophets. They come to you dressed like sheep, but inside they are vicious wolves. You will know them by their fruit. Do people get bunches of grapes from thorny weeds, or do they get figs from thistles? In the same way, every good tree produces good fruit, and every rotten tree produces bad fruit. A good tree can’t produce bad fruit. And a rotten tree can’t produce good fruit. Every tree that doesn’t produce good fruit is chopped down and thrown into the fire. Therefore, you will know them by their fruit.
[CEB (2011)]

Beware of false prophets, who come to you in sheep’s clothing but inwardly are ravenous wolves. You will know them by their fruits. Are grapes gathered from thorns or figs from thistles? In the same way, every good tree bears good fruit, but the bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. Every tree that does not bear good fruit will be cut down and thrown into the fire. Thus you will know them by their fruits.
[NRSV (2021 ed.)]

Watch out for false prophets. They come to you in sheep’s clothing, but inwardly they are ferocious wolves. By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles? Likewise, every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Thus, by their fruit you will recognize them.
[NIV (2011 ed.)]