Gregory the Great
Catena Aurea · Lukasevangelium 10
And into whatever house ye enter, first say, Peace be to this house. And if the son of peace be there, your peace shall rest upon it: if not, it shall turn to you again. And in the same house remain, eating and drinking such things as they give; for the labourer s worthy of his hire. Go not from house to house. And into whatsoever city ye enter, and they receive you, eat such things as are set before you: And heal the sick that are therein, and say unto them, The kingdom of God is come nigh unto you. But into whatsoever city ye enter, and they receive you not, go your ways out into the streets of the same, and say, Even the very dust of your city, which cleaveth on us, we do wipe off against you: notwithstanding be ye sure of this, that the kingdom of God is come nigh unto you. But I say unto you, that it shall be more tolerable in that day for Sodom, than for that city.
(ubi sup.) For now the very food which supports him is part of the wages of the labourer, as in this life the hire commences with the labour of preaching, which in the next is completed with the sight of truth. And here we must consider that two rewards are due to one work of ours, one on the journey, which supports us in labour, the other in our country, which recompenses us at the resurrection. Therefore the reward which we receive now ought so to work in us, that we the more vigorously strive to gain the succeeding reward. Every true preacher then ought not so to preach, that he may receive a reward at the present time, but so to receive a reward that he may have strength to preach. For whoever so preaches that here he may receive the reward of praise, or riches, deprives himself of an eternal reward.