When I was a boy I heard it stated concerning Oliver Cowdery, that after he left the Church he practised law, and upon one occasion, in a court in Ohio, the opposing counsel thought he would say something that would overwhelm Oliver Cowdery, and in reply to him in his argument he alluded to him as the man that had testified and had written that he had beheld an angel of God, and that angel had shown unto him the plates from which the Book of Mormon was translated. He supposed, of course, that it would cover him with confusion, because Oliver Cowdery then made no profession of being a “Mormon,” or a Latter-day Saint; but instead of being affected by it in this manner, he arose in the court, and in his reply stated that, whatever his faults and weaknesses might be, the testimony which he had written, and which he had given to the world, was literally true.
The passage occurs in a broader Sabbath sermon Cannon delivered on the divine origin and witnesses of the Book of Mormon. Cannon prefaces the courtroom anecdote by recounting that "three witnesses, in addition to the man who was chosen of God, to translate it, testify, in the most solemn manner that an holy angel came and exhibited the plates and testified to them that it was of God" — noting that all three witnesses "maintained their testimony unflinchingly" even after their alienation from the Church.