New Revised Standard Version
John said to the crowds that came out to be baptized by him, “You brood of vipers! Who warned you to flee from the wrath to come?

Contemporary English Version
Crowds of people came out to be baptized, but John said to them, "You bunch of snakes! Who warned you to run from the coming judgment?

New American Bible
He said to the crowds who came out to be baptized by him, “You brood of vipers! Who warned you to flee from the coming wrath?

Douay-Rheims Bible
He said therefore to the multitudes that went forth to be baptized by him: Ye offspring of vipers, who hath shewed you to flee from the wrath to come?

He said therefore to the multitudes that went forth to be baptized by him: Ye offspring of vipers, who hath shewed you to flee from the wrath to come?

O generation.

Genesis 3:15 I will put enmities between thee and the woman, and thy seed and her seed: she shall crush thy head, and thou shalt lie in wait for her heel.

Psalm 58:4,5 Their madness is according to the likeness of a serpent: like the deaf asp that stoppeth her ears: . . .

Isaiah 59:5 They have broken the eggs of asps, and have woven the webs of spiders: he that shall eat of their eggs, shall die: and that which is brought out, shall be hatched into a basilisk.

Matthew 3:7-10 And seeing many of the Pharisees and Sadducees coming to his baptism, he said to them: Ye brood of vipers, who hath shewed you to flee from the wrath to come? . . .

Matthew 23:33 You serpents, generation of vipers, how will you flee from the judgment of hell?

John 8:44 You are of your father the devil: and the desires of your father you will do. He was a murderer from the beginning: and he stood not in the truth, because truth is not in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father thereof.

Acts 13:10 Said: O full of all guile and of all deceit, child of the devil, enemy of all justice, thou ceases not to pervert the right ways of the Lord.

1 John 3:8 He that committeth sin is of the devil: for the devil sinneth from the beginning. For this purpose the Son of God appeared, that he might destroy the works of the devil.

to flee.

1 Thessalonians 1:10 And to wait for his Son from heaven (whom he raised up from the dead), Jesus, who hath delivered us from the wrath to come.

Hebrews 6:18 That by two immutable things in which it is impossible for God to lie, we may have the strongest comfort, we who have fled for refuge to hold fast the hope set before us.