John Whitmer briefly mentions Three Witnesses in his ca. 1835–38 history.
John Whitmer, History, 1831–circa 1847, 25, The Joseph Smith Papers website, accessed February 13, 2023
Permit me here to remark, that David Whitmer, Oliver Cowdery, and Martin Harris, were the three Witnesses, whose names are attached to the Book of Mormon according to the prediction of the Book, who knew and seen, for a surity, into whose presence the anger [angel] of God came and showed them the Plates, the ball, the directers, &c. And also other witnessees even eight Viz. Christian Whitmer, Jacob Whitmer, John Whitmer, Peter Whitmer Jr. Hyram [Hiram] Page, Joseph Smith [Sr.], Hyram [Hyrum] Smith, and Samuel H. Smith. are the men to whom Joseph Smith Jr showed the Plates, these witnesses names go forth also of the truth of this work in the last days. To the convincing or condemning of this generation in the last day.