“God’s grace does not terminate in the recipient, but it is to be reproduced in generosity. This is the “proof of love” and of obedience to the confession of Christ through the gospel.” (cf. 2 Cor 8:8, 24)
Paul Barnett, The Second Epistle to the Corinthians NICNT (Grand Rapids: Eerdmans, 1997) 448-449.