Hilary of Poitiers
Catena Aurea · Matthäusevangelium 10
He that receiveth you receiveth me, and he that receiveth me receiveth him that sent me. He that receiveth a prophet in the name of a prophet shall receive a prophet’s reward; and he that receiveth a righteous man in the name of a righteous man shall receive a righteous man’s reward. And whosoever shall give to drink unto one of these little ones a cup of cold water only in the name of a disciple, verily I say unto you, he shall in no wise lose his reward.
Or; Seeing beforehand that there would be many who would only glory in the name of Apostleship, but in their whole life and walk would be unworthy of it, He does not therefore deprive of its reward that service which might be rendered to them in belief of their religious life. For though they were the very least, that is, the greatest of sinners, yet even small offices of mercy shewn them, such as are denoted by the cup of cold water, should not be shewn in vain. For the honour is not done to a man that is a sinner, but to his title of disciple.