Theophylact of Ohrid
Catena Aurea · Lukasevangelium 10
And the seventy returned again with joy, saying, Lord, even the devils are subject unto us through thy name. And he said unto them, I beheld Satan as lightning fall from heaven. Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy: and nothing shall by any means hurt you. Notwithstanding in this rejoice not, that the spirits are subject unto you; but rather rejoice, because your names are written in heaven.
Or serpents are those which visibly hurt, as the evil spirit of adultery and murder. But those are called scorpions which invisibly injure, as in the sins of the spirit.