'Vipers' in the Bible

But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come?

O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.

Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?

Then said he to the multitude that came forth to be baptized of him, O generation of vipers, who hath warned you to flee from the wrath to come?