As you know how we exhorted, comforted, and implored every one of you, as a father does his own children,
Testifying ...  This is an unfortunate rendition because of its usual interpretation of "sounding off"' in public meetings.  It is not that kind of "testifying" that Paul meant.  The Nestle Greek rendition (see footnote) renders this, "As ye know how we exhorted and comforted and charged every one of you."  That this is the proper word appears from the account of what was "witnessed" as recounted in  1 Thessalonians 2:12, immediately afterward.