John Calvin Commentary 2 Corinthians 8:11

"But now complete the doing also; that as [there was] the readiness to will, so [there may be] the completion also out of your ability." — 2 Corinthians 8:11 (ASV)

Now what you have begun to do. It is probable that the zeal of the Corinthians had quickly cooled down; otherwise, they would, without any delay, have pursued their purpose. The Apostle, however, as though no fault had yet been committed, gently admonishes them to complete what had been well begun.

When he adds — from what you have, he anticipates an objection; for the flesh is always ingenious in finding excuses. Some plead that they have families, which it would be inhuman to neglect; others, on the ground that they cannot give much, make use of this as a pretext for entire exemption.

Could I give so small a sum? Paul removes all excuses of this nature when he commands everyone to contribute according to the measure of his ability.

He also adds the reason: that God looks to the heart — not to what is given. For when he says that readiness of mind is acceptable to God according to the individual’s ability, his meaning is this — “If from slender resources you present some small sum, your disposition is not less esteemed in the sight of God than in the case of a rich man’s giving a large sum from his abundance. (Mark 12:44) For the disposition is not estimated according to what you do not have; that is, God by no means requires of you that you contribute more than your resources allow.”

In this way, none are excused. For the rich, on the one hand, owe God a larger offering, and the poor, on the other hand, should not be ashamed of their slender resources.