Paul continues the theme of the collection for Jerusalem. He has boasted of Achaia's readiness, which stirred up many in Macedonia. He is sending brothers ahead so that, if Macedonians come with him, neither he nor the Corinthians will be embarrassed. The gift should be ready as a willing blessing, not as an extortion.
Paul applies a principle from farming and wisdom literature. Whoever sows sparingly will reap sparingly, and whoever sows bountifully will reap bountifully. Each one should give as he has decided in his heart, not with regret or under compulsion, because God loves a cheerful giver (9:7). God is able to make all grace abound, so that believers have enough at all times and can do every good work. Paul quotes Psalm 112, which describes the righteous person who scatters gifts to the poor.
The God who supplies seed and bread will multiply their resources and enlarge the harvest of their righteousness. Generosity has a vertical result as well as a horizontal one. It supplies the needs of the saints and overflows in many thanksgivings to God. The Jerusalem believers will glorify God for the Corinthians' obedient confession of the Good News, and they will pray for them with longing. The chapter rises to doxology: thanks be to God for His indescribable gift, the gift of Christ that lies behind all Christian giving.