Matthew 3:7

But when John saw that many of the Pharisees and Sadducees were coming for baptism, he said: "O brood of vipers! Who has warned you to flee from the wrath to come?

Matthew 23:33

"You serpents! You vipers brood! How shall you escape the judgment of hell?

Romans 3:13

Their throat is an open grave; With their tongues they have used deceit. The venom of asps is under their lips.

James 3:8

no man can tame the tongue, restless evil that it is, full of deadly poison.

Treasury of Scripture Knowledge

Summary

Their poison is like the poison of a serpent: they are like the deaf adder that stoppeth her ear;

Bible References

Poison

Romans 3:13
Their throat is an open grave; With their tongues they have used deceit. The venom of asps is under their lips.
James 3:8
no man can tame the tongue, restless evil that it is, full of deadly poison.