A venomous serpent
Dan shall be a serpent by the way, an adder in the path, that biteth the horse heels, so that his rider shall fall backward. (Genesis 49:17)
Thou shalt tread upon the lion and adder: the young lion and the dragon shalt thou trample under feet. (Psalm 91:13)
Their poison is like the poison of a serpent: they are like the deaf adder that stoppeth her ear; (Psalm 58:4)
They have sharpened their tongues like a serpent; adders' poison is under their lips. Selah. (Psalm 140:3)
At the last it biteth like a serpent, and stingeth like an adder. (Proverbs 23:32)