Theophylact of Ohrid
Catena Aurea · Lukasevangelium 9
Then there arose a reasoning among them, which of them should be greatest. And Jesus, perceiving the thought of their heart, took a child, and set him by him, And said unto them, Whosoever shall receive this child in my name receiveth me: and whosoever shall receive me receiveth him that sent me: for he that is least among you all, the same shall be great. And John answered and said, Master, we saw one casting out devils in thy name; and we forbad him, because he followeth not with us. And Jesus said unto him, Forbid him not: for he that is not against us is for us.
Now it seems that this feeling was excited by the circumstance of their not being able to cure the demoniac. And while they were disputing thereupon, one said, It was not owing to my weakness, but another’s, that he could not be cured; and so thereby was kindled a strife among them, which was the greatest.