A passage that will likely go unmentioned by anyone — hence, my choice — is 1 Thess. 2:2: “But although we suffered earlier and were mistreated in Philippi, as you know, we had the courage in our God to declare to you the gospel of God in spite of much opposition.”
When Paul left Philippi, he seems to have gone without delay to Thessalonica. Luke says he passed “through Amphipolis and Apollonia” on his way there, apparently without stopping (Acts 17:1). (Alternatively, it is evidence for their sincerity.) The mistreatment he suffered in Philippi must have marked him, for him to mention it as he did to the Thessalonians. He and Silas had been beaten “severely” with rods, in public (Acts 16:23). It was in Thessalonica that he recovers from that beating and he must have still bore its marks when he preached in the synagogue of that city.
It would appear, then, that Paul was “deeply hurt” by the Philippian mistreatment (NASV Study Bible). It would seem that he had to muster the courage to continue to preach in Thessalonica and found it “in our God to declare to you the gospel of God in the midst of much conflict.” The term “conflict” this this context “seems to suggest inner conflict which has risen due to external opposition” (R. C. Kelcy, Thessalonians, LWC, 40).
This is not Paul’s first hardship, however. He has weathered worse. Before this, on his first missionary journey, in Lystra, he had been stoned by Jews from Antioch and Iconium and left for dead (Acts 14:19). Perhaps he had a harder time “suffer[ing] many hardships” (Acts 14:22) injustly at the hands of the Romans than from the Jews.
However that may be, Paul did find the courage to preach in the next big city down the road, after the humiliation suffered in Philippi. Courage in our God. When men shrink from the trials and mere humans fail in their bluster, we find in our God the stiffness of spine to continue his mission in the world.