John Calvin Commentary Isaiah 11:8

"And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the adder`s den." — Isaiah 11:8 (ASV)

And the child shall play on the hole of the asp. He continues to illustrate the same sentiment, that when people have been brought into a state of favor with God, and have been cleansed from their depravity by the Spirit of regeneration, they will also be free from every harmful disposition. There is no reason why people dread the danger or poison from the bite of serpents, except because they do not deserve that God should place every part of the world under their control. And indeed, since animals are permitted to cause harm even to children, this shows that the whole race of Adam has been stained with pollution from the very womb.

We must again observe the comparison we stated, that those people whom a concealed poison led to deeds of violence will have their disposition changed, and will do no harm even to little children. Some people are openly fierce and cruel (Psalms 140:3), and others inwardly carry and cherish their malice like poison (Psalms 55:21), as David also describes them. For some people are quicker, and others are slower, to manifest the desire to cause harm. Whatever they may have formerly been, he means that all of them must be cleansed from wickedness, both open and concealed, after having submitted to Christ. He also means that from now on, safety, which will reign everywhere, will be enjoyed even by those who have no kind of protection, so that they will freely venture to expose themselves to imminent dangers.