Pseudo-Chrysostom
Catena Aurea · Markusevangelium 9
And John answered him, saying, Master, we saw one casting out devils in thy name, and he followeth not us: and we forbad him, because he followeth not us. But Jesus said, Forbid him not: for there is no man which shall do a miracle in my name, that can lightly speak evil of me. For he that is not against us is on our part. For whosoever shall give you a cup of water to drink in my name, because ye belong to Christ, verily I say unto you, he shall not lose his reward. And whosoever shall offend one of these little ones that believe in me, it is better for him that a millstone were hanged about his neck, and he were cast into the sea.
(Vict. Ant. e Cat. in Marc.) Or else, this is said of those who believe on Him, but nevertheless do not follow Him from the looseness of their lives. Again, it is said of devils, who try to separate all from God, and to disperse His congregation. There follows, For whosoever shall give you a cupof cold water to drink in my name, because ye belong to Christ, verily I say unto you, he shall not lose his reward.