Jamieson, Fausset & Brown, on 1Cor 9:14

Even so--The only inference to be drawn from this passage is, not that the Christian ministry is of a sacrificial character as the Jewish priesthood, but simply, that as the latter was supported by the contributions of the people, so should the former. The stipends of the clergy were at first from voluntary offerings at the Lord's Supper. At the love-feast preceding it every believer, according to his ability, offered a gift; and when the expense of the table had been defrayed, the bishop laid aside a portion for himself, the presbyters, and deacons; and with the rest relieved widows, orphans, confessors, and the poor generally [TERTULLIAN, Apology, 39]. The stipend was in proportion to the dignity and merits of the several bishops, presbyters, and deacons [CYPRIAN, c. 4, ep. 6]. preach . . . gospel--plainly marked as the duty of the Christian minister, in contrast to the ministering about sacrifices (Greek) and waiting at the altar of the Jewish priesthood and Levites (Co1 9:13). If the Lord's Supper were a sacrifice (as the Mass is supposed to be), this fourteenth verse would certainly have been worded so, to answer to Co1 9:13. Note the same Lord Christ "ordains" the ordinances in the Old and in the New Testaments (Mat 10:10; Luk 10:7).