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.) And that no man may allege poverty, He mentions that, of which none can be destitute, that is, a cup of cold water, for which also he will obtain a reward; for it is not the value of the gift, but the dignity of those who receive it, and the feelings of the giver, which makes a work worthy of reward. His words shew that His disciples are to be received, not only on account of the reward, which he who receives them obtains, but also, because he thus saves himself from punishment. There follows: 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: as though He would say,1 All who honour you for My sake have their reward, so also those who dishonour you, that is, offend you, shall receive the worst of vengeance. Further, from things which are palpable to us, He describes an intolerable torment, making mention of a millstone, and of being drowned; and He says not, let a millstone be hanged about his neck, but, it is better for him to suffer this, shewing by this that some more heavy evil awaits him. But He means by little ones that believe on Me, not only those who follow Him, but those who call upon His name, those also who offer a cup of cold water, though they do not any greater works. Now He will have none of these offended or plucked away; for this is what is meant by forbidding them to call upon His name.