1 Thessalonians 2:2
But even after that we had suffered before, and were shamefully entreated, as ye know, at Philippi, we were bold in our God to speak unto you the gospel of God with much contention.
Note 2 at 1Th 2:2: Philippi is a city about eighty-five miles northeast of Thessalonica. It would have taken Paul about three or four days to travel that distance by foot.
Paul referred to his treatment in Philippi as shameful. Paul and Silas were arrested and, without a trial, beaten and thrown into prison (Ac 16:10-40). As Roman citizens, this treatment was illegal (see note 2 at Ac 16:37).
Despite the sufferings they had endured because of their preaching of the Gospel, they were bold to share the same truths with the Thessalonians.