1 Corinthians 9

The NKJV says this: Paul had the right to eat and drink whatever he wanted, to have a wife, and to receive wages for his ministry.
But he did not exercise these rights. God requires that ministers should be paid for their work just as He requires beasts of burden to be compensated for theirs. To support ministers of the gospel is commanded by God.

Paul put his ministry of the gospel above his personal desires. He was willing to conform to the customs of other people, whether Jew or Gentile, in order to bring them to Christ. For example, in order to relate to the Jews in Jerusalem he made a Nazirite vow in the temple (Acts 21:23, 24). Around those who were under the Law—the Jews—Paul obeyed the Law. Around those who were outside the Law—the Gentiles—Paul did not observe Jewish custom. Paul clarified this, however, lest anyone misunderstand his actions. He obeyed God's law through obedience toward Christ . This was a broader law than the Mosaic legislation; this was the fulfillment of Christ's will.

The Greek word for disqualified means "disapproved after testing." Although some have cited this verse as evidence that Christians can lose their salvation, this clause most likely does not refer to salvation. A careful distinction should be made between the prize and the gift. The free gift of justification cannot be the result of good works (see Rom. 4:1–8). However the prize or crown is the reward for endurance and suffering for the cause of Christ.

9
Am I not an apostle? Am I not free? Have I not seen Jesus Christ our Lord? Are you not my work in the Lord? 2 If I am not an apostle to others, yet doubtless I am to you. For you are the seal of my apostleship in the Lord.

3 My defense to those who examine me is this: 4 Do we have no right to eat and drink? 5 Do we have no right to take along a believing wife, as do also the other apostles, the brothers of the Lord, and Cephas? 6 Or is it only Barnabas and I who have no right to refrain from working? 7 Who ever goes to war at his own expense? Who plants a vineyard and does not eat of its fruit? Or who tends a flock and does not drink of the milk of the flock?

8 Do I say these things as a mere man? Or does not the law say the same also? 9 For it is written in the law of Moses, "You shall not muzzle an ox while it treads out the grain." Is it oxen God is concerned about? 10 Or does He say it altogether for our sakes? For our sakes, no doubt, this is written, that he who plows should plow in hope, and he who threshes in hope should be partaker of his hope. 11 If we have sown spiritual things for you, is it a great thing if we reap your material things? 12 If others are partakers of this right over you, are we not even more?

Nevertheless we have not used this right, but endure all things lest we hinder the gospel of Christ. 13 Do you not know that those who minister the holy things eat of the things of the temple, and those who serve at the altar partake of the offerings of the altar? 14 Even so the Lord has commanded that those who preach the gospel should live from the gospel.

15 But I have used none of these things, nor have I written these things that it should be done so to me; for it would be better for me to die than that anyone should make my boasting void. 16 For if I preach the gospel, I have nothing to boast of, for necessity is laid upon me; yes, woe is me if I do not preach the gospel! 17 For if I do this willingly, I have a reward; but if against my will, I have been entrusted with a stewardship. 18 What is my reward then? That when I preach the gospel, I may present the gospel of Christ without charge, that I may not abuse my authority in the gospel.

19 For though I am free from all men, I have made myself a servant to all, that I might win the more; 20 and to the Jews I became as a Jew, that I might win Jews; to those who are under the law, as under the law, that I might win those who are under the law; 21 to those who are without law, as without law (not being without law toward God, but under law toward Christ), that I might win those who are without law; 22 to the weak I became as weak, that I might win the weak.
I have become all things to all men, that I might by all means save some.
23 Now this I do for the gospel's sake, that I may be partaker of it with you.

24 Do you not know that those who run in a race all run, but one receives the prize? Run in such a way that you may obtain it. 25 And everyone who competes for the prize is temperate in all things. Now they do it to obtain a perishable crown, but we for an imperishable crown. 26 Therefore I run thus: not with uncertainty. Thus I fight: not as one who beats the air. 27 But I discipline my body and bring it into subjection, lest, when I have preached to others, I myself should become disqualified.