“For as the rain and the snow come down from heaven and do not return there but water the earth, making it bring forth and sprout, giving seed to the sower and bread to the eater, so shall my word be that goes out from my mouth; it shall not return to me empty, but it shall accomplish that which I purpose, and shall succeed in the thing for which I sent it. (Isaiah 55:10-11 ESV)
By Stephen W. Hiemstra
The Prophet Isaiah draws a parallel between the generosity of God in watering the earth and the word of God powerfully accomplishing his purposes. Because generosity is a tangible expression of love, is Isaiah, in fact, saying that love accomplishes God’s purposes? Jesus thought so (Matthew 5:44-46).
In chapter 9, Paul continues his discussion of the drought relief fund for Jerusalem that he has been discussing. Garland  noted these parallels between chapters 8 and 9 forming an inclusio (a literary frame around the discussion):
|The grace of God||8:1||9:14|
This is inclusio is important because other commentaries have argued for a second letter being inserted in chapter 9 because they could not understand Paul’s apparent repetition. Paul pauses in his letter to explain the relief fund, in part, because his Greek audience does not understand the Jewish concern for helping the poor.
For example, in verse 9 Paul paraphrases: You shall give to him freely, and your heart shall not be grudging when you give to him, because for this the LORD your God will bless you in all your work and in all that you undertake. (Deuteronomy 15:10) Like the Romans, the Greeks saw only one reason for charity—to receive praise and honor from those receiving it. Praise and honor from poor people was not interesting to them. Praise and honor from God for offering charity to the poor, by contrast, was another matter. In verses 7-12, Paul reminds them of God’s interest in generosity, especially to the poor, 4 times!
Paul drives his point home by reminding the Corinthians that the saints in Jerusalem will be praying for them (v 14) .
Generosity. Do we count both the blessings and the cost when we donate money? Paul reminds us: God loves a cheerful giver (v 7)
 David E. Garland. 1999. The New American Commentary: 2 Corinthians. Nashville: B&H. page 400.
 Later, in his letter to the Romans (15:30-31), Paul worries that the Corinthian gift will not be accepted.