Gregory the Dialogist

Ver. 16. He shall suck the head of asps: the viper's tongue shall slay him. 19. The 'asp' is a small serpent, but the 'viper' hath more length of body. And asps produce eggs, and their young are hatched from the eggs. But when vipers have conceived, their 'young ravin in their womb, which bursting the parents' sides issue out of their bellies. …

Morals on the Book of Job, Book XV ↗

Thomas Aquinas

Not only the goods which he possessed will change into evil for him, but also he will suffer evils at the hands of his enemies both in word and in deed. He gives two examples of this. First, he gives the example of the asp which kills by its bite. So he says, "The asps raise their head," against him to bite him. By this he means the head of evildoers, or even Satan himself attacking him. As the second example he gives the viper which distributes its poison with the tongue. …

Commentary on Job ↗