A few sources:
“[W]hen the mob again assembled, they went to the houses of several of the leading Mormons; and, taking Isaac Morley, David Whitmer, and others, they told them to bid their families farewell, for they would never see them again. Then driving them at the point of the bayonet to the public square, they stripped and tarred and feathered them, amidst menaces and insults. The commanding officer then called twelve of his men, and ordering them to cock their guns and present them at the prisoner's breasts, and to be ready to fire when he gave the word,--he addressed the prisoners, threatening them with instant death, unless they denied the Book of Mormon and confessed it to be a fraud; at the same time adding, that if they did so, they might enjoy the privileges of citizens. David Whitmer, hereupon, lifted up his hands and bore witness that the Book of Mormon was the Word of God. The mob then let them go.”
John P. Greene, Facts Relative to the Expulsion of the Mormons or Latter-day Saints, from the State of Missouri, Under the "Exterminating Order" (1839), http://www.boap.org/LDS/Early-Saints/Jersey Girl ... souri.html.
“I have been surrounded by hostile mobs, on one occasion numbering four or five hundred, demanding I should deny what is published over my name in the Book of Mormon; but the testimony I gave to that mob made them fear and tremble, and I escaped from them. One gentleman, a doctor, an unbeliever, told me afterwards that the bold and fearless testimony borne on that occasion and the fear that seemed to take hold of the mob had made him a believer in the Book of Mormon.”
Letter from James H. Hart, Deseret Evening News, Sept. 4, 1883, p. 2, https://newspapers.lib.utah.edu/file?id=23176783 (third column from left).