Giving

2 Corinthians 8:1 KJV
Moreover, brethren, we do you to wit of the grace of God bestowed on the churches of Macedonia;

Sometimes remembering the most basic of principles is very helpful. Scofield's notes says the following concerning 2 Corinthians 8-9 and giving:
"In 2 Corinthians 8-9, the apostle sums up the Christian doctrine of giving. It may be thus summarized:
(1) It is a "grace," that is, a disposition created by the Spirit. (2 Cor 8:7).
(2) In contrast with the law, which imposed giving as a divine requirement, Christian giving is voluntary, and a test of sincerity and love. (2 Cor 8:8-12); (2Cor 9:1); (2 Cor 9:2); (2 Cor 9:5); (2 Cor 9:7).
(3) The privilege is universal, belonging, according to ability, to rich and poor. (2 Cor 8:1-3); (2 Cor 8:12-15); (1 Cor 16:1); (1 Cor 16:2).
(4) Giving is to be proportioned to income. (2 Cor 8:12-14); (1 Cor 16:2). The Old Testament proportion was the tithe, a proportion which antedates the law. (Gen 14:20).
(5) The rewards of Christian giving are:
(a) Joy. (2 Cor 8:2).
(b) Increased ability to give in proportion to that which has been already given. (2 Cor 9:7-11).
(c) Increased thankfulness to God. (2 Cor 9:12).
(d) God and the Gospel glorified. (2 Cor 9:13); (2 Cor 9:14)."