Paul knew that his visit to Jerusalem would be dangerous because the Holy Spirit had told him that prison and hardships awaited him (Acts 20:22-24).  That would be confirmed by a specific prophecy (Acts 21:10-14).  But at the time of writing his letter, all he knew was that the unbelieving Jews would be a threat to his life, but those who trusted in Christ needed great encouragement.  In this prayer request, Paul asks that the money collected for the impoverished Christians in Jerusalem would get through to them safely.  After that he hoped to travel to Rome en route for Spain (Romans 15:24-29).

A detailed account of what actually happened is found in Acts chapters 21-28.  The apostolic team did arrive safely at Jerusalem with the money but, after that, the Jews stirred up a riot.  However, Paul was protected by the military commander, although under arrest.  As a Roman citizen he had special rights which enabled him to speak the gospel clearly in Jerusalem; then he was imprisoned in Israel for two years and was eventually sent under guard to Rome.  

Was Paul’s prayer request wrong or did God fail to answer the prayers?  Neither.  It was right for Paul to be aware of the dangers and ask to be spared from them, as Jesus did in Gethsemane (Matthew 26:39).  And God has the right to answer every prayer according to His will, as Jesus found (Matthew 26:42).  That might help us to understand that although Paul was not spared, God’s purpose for Paul to preach in Rome was fulfilled (Acts 23:11).  While there, he stayed in his own rented house for at least another two years preparing for his trial.  So, his prayer request was answered, but not in the easy way he supposed.  But by 'God's will' Paul did go to Rome and refreshed the church there as he preached.  Also, his letters from prison to other churches have formed much of our New Testament and shaped the church worldwide for the last two millennia.

As we plan and pray, God knows exactly how He wants to answer our prayers and also fulfil His purposes through us.  In one way, it makes prayer more exciting!  God is not a shopkeeper from whom we order what we want.  He understands our needs, and also knows how He is going to blend the answer to our prayers to achieve His larger purposes.  So, when our prayers are not answered as we expect, we should not be distressed.  God knows exactly what He is doing, and His way of achieving it is infinitely superior to ours.  If we do not trust Him, we will be confused, upset and disappointed.  But when we trust Him to exercise His right to be God, we will fulfil our calling and He will get the glory.