Romans 15:25

But now I go unto Jerusalem
Whither he was bound in spirit, not knowing what should befall him there, from which he could not be dissuaded by his friends, and thither he did go:

to minister unto the saints;
not to preach the Gospel, though doubtless he did that when he was there; but to distribute among the poor saints what had been raised for them by the Greek churches; who had entreated him to take upon him this service, even the fellowship of ministering to the saints; and though this might seem below his office as an apostle, and as what more became an inferior officer, a deacon in a church; yet the apostle's heart was so much in it, and he was so bent upon it, and so diligent to execute it, that he postponed his journey to Spain and visit to Rome for the sake of it, and assigns this as a reason why he could not come at present.