Supporting the one that ministers (1 Cor. 9).
Wherever he traveled, Paul worked with his own hands as a tent-maker for his personal needs (Acts 20:33-34). On occasion, when he was in need, Paul would receive support from individuals and assemblies, such as the Philippians, who "sent once and again unto my necessity" (Phil. 4:16). Paul had never taken money from the Corinthians (2 Cor. 12:13-14), who were relatively wealthy. He speaks of "robbing other churches" (2 Cor. 11:8-9). In 1 Cor. 9 we have a little light on why Paul chose not to receive financial support from the Corinthians: because it left him free to preach and teach whatever the Lord asked him, without any possibility of an accusation of corruption. There was a worldly spirit among the Corinthians, and Paul felt it might compromise his ministry to take what was rightfully his from the Corinthians. Paul also wouldn't receive from the Thessalonians because he wanted to set a good example to them as new converts (1 Thess. 2:9), and also because some among them had a problem with laziness (2 Thess. 3:6-12). Nevertheless, scripture is clear that it is right and proper for believers to financially support those that serve them (1 Cor. 9:9; 1 Tim. 5:18; Gal. 6:6), and it is a tremendous privilege to do so, and an opportunity to further the cause of Christ (Phil. 4:17). Of course, support for Christ's servants is not limited to giving money only. It is equally important to show hospitality to these ones (3 John 1:5-8).
Sending aid to the poor (1 Cor. 16; 2 Cor. 8-9). Giving to the poor is an important part of Christianity. As individuals, we are to be very forward in giving to the poor of this world, feeding the hungry, etc. as we have in our Lord’s own ministry, and displayed in His own habits (Matt. 6:3; Matt. 19:21; Matt. 26:11; Luke 12:33; John 13:29). See also Acts 10:2 and 1 Cor. 13:3. But concerning the collection, its primary use is for the saints, hence it is called "the collection for the saints" (1 Cor. 6:1). The assembly ought to take care of the poor within the Christian company first. This could take place at a local level, and also at a global level. We have instructions for the assembly to give to the widows indeed (1 Tim. 5) and even perhaps the fatherless (James 1:27). But Paul, on his missionary journeys, was seeking to stir up the wealthy Gentile believers to send a collection to the poor saints in Jerusalem. It was fitting that the apostle to the uncircumcision be the one to round-up these funds. Paul and Barnabas had delivered an earlier collection to relieve the needs of the brethren there in Jerusalem (Acts 11:27-30), and he had arranged with Peter to do so again before leaving on his second journey (Gal. 2:10). Then, upon returning from his third journey, Paul delivered it (Acts 24:17; Rom. 15:25-26). The brethren in Judea were in a state of continual poverty since the very earliest days of the Church, as a result of three things: first, they had sold their possessions in unselfish love to have all things common (Acts 4:32); second, there arose a great famine in the days of Claudius Caesar (Acts 11:27-30); and third, they suffered the spoiling of their goods by those who opposed and persecuted them (Heb. 10:34). The collection was gathered by the assemblies in Macedonia or northern Greece, and Achaia or southern Greece (Acts 24:17; Rom. 15:25-26). The Macedonians were relatively poor, and yet had given more readily (2 Cor. 8:2). The Corinthians were quite wealthy, but having started to pull the funds together, and hearing that Paul’s visit was delayed for one year, had not finished the collection. Paul wrote to them encouraging them to finish, just as they had intended. Rom. 15:25 shows us that they did eventually finish the collection, and Paul carried it with him to Jerusalem!