The Apostle Paul
1 Thessalonians 2:2ESV·traditional attribution

But though we had already suffered and been shamefully treated at Philippi, as you know, we had boldness in our God to declare to you the gospel of God in the midst of much conflict.

Matthew Henry Presbyterian @wholebiblehenry

Here we have an account of Paul's manner of preaching, and his comfortable reflection upon his entrance in among the Thessalonians. As he had the testimony of his own conscience witnessing to his integrity, so he could appeal to the Thessalonians how faithful he, and Silas, and Timotheus, his helpers in the work of the Lord, had discharged their office: You yourselves, brethren, know our entrance in unto you.

Commenting on 1 Thessalonians 2:1-6

John Gill Reformed Baptist @doctorgill

But even after that we had suffered before,.... Before they came to Thessalonica, which they would not have done, had their ministry been a light and empty one in itself, and unprofitable to others; and especially had this been the case, they would never have rashly engaged in it again, and exposed themselves to fresh sufferings and dangers, as they did: and were shamefully entreated...

Albert Barnes Presbyterian @notesbybarnes

Verse 2. But even after that we had suffered before. Before we came among you. And were shamefully entreated, as ye know, at Philippi, , seq. By being beaten and cast into prison. The shame of the treatment consisted in the fact that it was wholly undeserved; that it was contrary to the laws; and that it was accompanied with circumstances designed to make their punishment as ignominious as possible.