2 Corinthians 9:7

7Every one according to the purpose of his heart. As he had enjoined it upon them to give liberally, this, also, required to be added — that liberality is estimated by God, not so much from the sum, as from the disposition. He was desirous, it is true, to induce them to give largely, in order that the brethren might be the more abundantly aided; but he had no wish to extort any thing 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. (720) Now the necessity meant you must understand to be 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 from the influence of others, having in the mean time an inclination to avoid it, if by any means we could, we do nothing in that case with alacrity — nothing with cheerfulness, but every thing 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 intimates that, on the other hand, the niggardly and reluctant are loathed 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. (721)