John Calvin on Acts 20:18

18. Ye know. Paul, in this sermon, standeth principally upon this, that lie may exhort those pastors of Ephesus, “Quos Ephesi creaverat pastores,” those whom he had appointed pastors at Ephesus. by his own example, to do their duty faithfully. For that is the true kind of censure, and by this means is authority purchased to doctrine, when the teacher prescribeth nothing “In verbis,” verbally. which he himself hath not done indeed before. And it was no unseemly thing for Paul to speak of his virtues. There is nothing less tolerable in the servants of Christ than ambition and vanity; but forasmuch as all men knew full well what modesty and humility was in the holy man, he needed not to fear lest he should incur the suspicion of vain boasting; especially, seeing that benign information by necessity, he did declare his faithfulness and diligence, that others might take example thereby. He doth, indeed, greatly extol his labors, patience, fortitude, and other virtues, but to what end? Surely not that he may purchase commendation at the hands of his auditory, but that his holy exhortation may pierce more deeply, and may stick fast in their minds. He did also shoot at another mark, that his integrity and uprightness in dealing might serve afterward to commend his doctrine. And he citeth eye-witnesses, lest he seem to speak of things unknown. I call those witnesses who did not only know all things, but had also a judgment which was pure, and corrupt with no affections.