1 Thessalonians 2:19-20
For what is our hope or joy or crown of boasting before our Lord Jesus at his coming? Is it not you? For you are our glory and joy.
1 Thessalonians was dashed off in a great hurry not long after Paul had been ridden out of town on a rail by persecution. He was very worried that the Thessalonians were wobbly on their feet as new (and persecuted) Christians and so he wrote to them to check up on them and see that everything was okay. To his great relief, things were fine and their reputation as gung-ho believers was rapidly spreading despite the grief they were getting from their neighbors. Paul founded no hospitals, established no schools, operated no high profile, multimillion dollar ministry. His only boast was a bunch of people who really loved Jesus. It was enough.