Catena Aurea on Mark 9:38–42: Pseudo-Chrysostom

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 cup of cold water to drink in My name, because ye belong to Christ, verily I say unto you, he shall not lose his reward.”