John Trapp (1601-1669) was an Anglican pastor and exegete. In reading 1 Cor 9:19, Trapp argues that as Paul made himself all things to all people, so should ministers do whatever is within their power to win the hearts of unbelievers and the joy that that accompanies their gain.

1 Corinthians 9:19

Though I am free and belong to no one, I have made myself a slave to everyone, to win as many as possible.

Commentary on 1 Corinthians 9:19

The Greek word for “gain” signifies among other things the joy and delight of the heart in gaining. It also signifies craft and guile, as is the case with the fox that, when he is very hungry after prey and can find none, lies down and pretends that he is a dead carcass. Thus when the birds light on him, he catches them. In the same way ministers must deny themselves to gain their hearers.

1 Corinthians, ed. Scott M. Manetsch, Reformation Commentary on Scripture, NT vol. 9a, p. 190.