'Vipers' in the Bible

But seeing many of the Pharisees and Sadducees coming to his baptism, he said to them, Offspring of vipers, who has forewarned you to flee from the coming wrath?

Offspring of vipers! how can ye speak good things, being wicked? For of the abundance of the heart the mouth speaks.

Serpents, offspring of vipers, how should ye escape the judgment of hell?