Whitmer says he never heard any other witnesses recant their testimonies.
John Whitmer, Letter, 5 March 1876 in Dan Vogel, Early Mormon Documents (Salt Lake City, UT: Signature Books, 2003), 5:242–243
Far West March 5, [18]76
Mark H Forest [sic] / Esq.
Dear Sir[:] Yours came duly to hand 4. Inst, and the contents considered.
I hasten to answer according to best of my information at hand.
Mrs. Cowdery Resides some place in Colorado. The address is mislaid, or I would give it.
However, I think I am able to answer your inquiries to your satisfaction
Oliver Cowdery lived in Richmond Mo. some 40 miles from here at the time of his Death. I went to see him and was with him for some days previous to his demise.
I have Never heard him deny the truth of his testimony of the Book of Mormon under any circumstances what ever.
I have no knowledge that there was any effort made to force him to deny the Book of Mormon. Neither do I believe that he would have denied at the peril of his life, so firm was he that he could not be moved to deny what he has affirmed to be <a> divine Revelation from God.
I desire to do good when it is in my power. I have never heard that any one of the three, or eight witnesses ever denied the testimony that they have borne to the Book as published in the first edition of the Book of Mormon
There are only two of the witnesses to that Book now living to wit. David Whitmer one of the three and [myself,] John Whitmer[,] one of the eight
Our names have gone forth to all Nations tongues and People as a Divine Revelation from God. And it will bring to pass the designs of God according to the declaration therein contained, &c.
Yours Respectfully,
[s] John Whitmer