'Snakes' in the Bible

But when he saw a number of the Pharisees and Sadducees coming to his baptism, he said to them, Offspring of snakes, at whose word are you going in flight from the wrath to come?

See, I send you out as sheep among wolves. Be then as wise as snakes, and as gentle as doves.

You offspring of snakes, how are you, being evil, able to say good things? because out of the heart's store come the words of the mouth.

You snakes, offspring of snakes, how will you be kept from the punishment of hell?