In Epistolam D. Pauli Apostoli ad Galatas notae

2 But I went up by revelation, and I explained to them the Gospel which I preach among the Gentiles: but privately to those who are in high standing, lest I might be running, or had run, in vain.

3 But neither was Titus, who was with me, being a Greek, compelled to be circumcised.

4 Indeed, because of the emissary false brothers who had crept in to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage.

The scope of Paul's journey was that the work of the Gospel might be preserved, both for the weak and for posterity. So let us also make an effort so that the building may be firm for posterity.

There is a similarity to those who run for a prize. It is not that the minister labors in vain, even if the whole world protests. For the Gospel always has its own fruit, which God wills that it should bring forth in individual sermons. To some it results in salvation; to others, in a testimony, through their own malice.

Matthew 24: The Gospel will be preached in the whole world as a testimony to them.

Therefore, the minister does not always labor in vain. Thus, 2 Corinthians 2: To others, the odor of death unto death, etc. And Chrysostom says, He who sows sometimes reaps nothing because of the cold, and loses his labor. But the minister, whether it grows or does not grow, will receive the reward of his labors.