A.T. Robertson Commentary Colossians 4:13

"For I bear him witness, that he hath much labor for you, and for them in Laodicea, and for them in Hierapolis." — Colossians 4:13 (ASV)

And for them in Hierapolis (κα των εν Hιερα Πολε). The third of the three cities in the Lycus Valley which had not seen Paul's face (2:1). It was across the valley from Laodicea. Probably Epaphras had evangelized all three cities and all were in peril from the Gnostics.