1 Thessalonians 2:10

On this account he frequently addresses them as witnesses. For "ye are witnesses," he says, "and God also"; God was worthy to be believed, but this other was that which most fully assured them. For that indeed was uncertain to those who were ignorant of it; but this was without doubt to all. For do not enquire whether it was Paul who said these things. Much beyond what was necessary he gives them assurance. Wherefore he says, "Ye are witnesses, and God also, how holily and righteously and unblamably we behaved ourselves toward you that believe." It was proper to praise them again. On this account he sets these things before them, which were sufficient to persuade them. For he that stood there in want, and did not receive anything, would much more not receive anything now. "How holily," says he, "and righteously and unblamably we behaved ourselves toward you that believe."