John Calvin Commentary 2 Corinthians 9:7

"[Let] each man [do] according as he hath purposed in his heart: not grudgingly, or of necessity: for God loveth a cheerful giver." — 2 Corinthians 9:7 (ASV)

Every one according to the purpose of his heart. As he had urged them to give liberally, this, also, needed to be added — that liberality is estimated by God not so much by the sum as by the disposition. He desired, it is true, to induce them to give generously, so that the brethren might be more abundantly helped; but he had no wish to extort anything from them against their will.

Hence he exhorts them to give willingly, whatever they might be prepared to give. He places purpose of heart in contrast with regret and constraint. For what we do when compelled by necessity is not done by us with purpose of heart, but with reluctance. Now, the necessity meant, you must understand, is what is extrinsic, as it is called — that is, what springs from the influence of others.

For we obey God because it is necessary, and yet we do it willingly. We ourselves, accordingly, in that case impose a necessity of our own accord; and because the flesh is reluctant, we often even constrain ourselves to perform a duty that is necessary for us. But when we are constrained by the influence of others, having in the meantime an inclination to avoid it if by any means we could, we do nothing in that case with eagerness — nothing with cheerfulness — but everything with reluctance or constraint of mind.

For God loveth a cheerful giver. He calls us back to God, as I said in the outset, for alms are a sacrifice. Now, no sacrifice is pleasing to God if it is not voluntary. For when he teaches us that God loveth a cheerful giver, he implies that, on the other hand, the miserly and reluctant are detested by Him. For He does not wish to lord it over us in the manner of a tyrant; but, as He acts towards us as a Father, so He requires from us the cheerful obedience of children.