that no one should take advantage of and wrong a brother or sister in this matter; because the Lord is an avenger in all these things, as also we forewarned you and testified.
as we also have forewarned you and testified: Paul’s teaching is always consistent. What he says orally is in perfect harmony with what he writes. What he says when he is present with the Thessalonians does not differ one whit from what he writes to them from a distant location at a later date. "Testified" has its usual New Testament meaning, "the announcement of God’s commands with exhortation to obey them" (Coffman 47).