When David was interviewed by Orson Pratt and Joseph F. Smith he recounted his experience with an angel in disguise while on the road to his home with Joseph and Oliver from Harmony, PA:
When I was returning to Fayette, with Joseph and Oliver, all of us riding in the wagon, Oliver and I on an old-fashioned, wooden, spring seat and Joseph behind us; while traveling along in a clear open place, a very pleasant, nice-looking old man suddenly appeared by the side of our wagon and saluted us with, “Good morning, it is very warm,” at the same time wiping his face or forehead with his hand. We returned the salutation, and, by a sign from Joseph, I invited him to ride if he was going our way. But he said very pleasantly, “No, I am going to Cumorah.” This name was something new to me, I did not know what Cumorah meant. We all gazed at him and at each other, and as I looked around inquiringly of Joseph, the old man instantly disappeared, so that I did not see him again.
J. F. S. Did you notice his appearance?
D. I should think I did. He was, I should think, about 5 feet 8 or 9 inches tall and heavy set, about such a man as James Vancleave there, but heavier; his face was as large, he was dressed in a suit of brown woolen clothes, his hair and beard were white, like Brother Pratt’s, but his beard was not so heavy. I also remember that he had on his back a sort of knapsack with something in, shaped like a book. It was the messenger who had the plates, who had taken them from Joseph just prior to our starting from Harmony (“Report of Elders Orson Pratt and Joseph F. Smith,” Millennial Star 40 (9 Dec 1878):771-7 ).
A second account was given by Edward Stevenson who also interviewed Whitmer:
While on the return journey from Palmyra, David noticed a somewhat aged-looking man who approached them on the road. He had a very pleasant face, about which, however, there seemed something peculiar, and he carried a knapsack on his back fastened with straps which crossed his breast. David asked him to take a ride, but he declined, saying: “I am going over to Cumorah,” and then disappeared very suddenly, though there was no chance for him to secrete himself in the open country through which the party was then passing. All felt very strange concerning this personage and the Prophet was besought to inquire of the Lord concerning him. Shortly afterwards, David relates, the Prophet looked very white but with a heavenly appearance and said their visitor was one of the three Nephites to whom the Savior gave the promise of life on earth until He should come in power. After arriving home, David again saw this personage, and mother Whitmer, who was very kind to Joseph Smith, is said to have seen not only this Nephite, but to have also been shown by him the sealed and unsealed parts of the plates from which the Book of Mormon was translated (Edward Stevenson, “Visit,” Instructor 22 (1887):55 ).
I wish to mention an Item of conversation with David Whitmer in regard to Seeing one of the Nephites, Zina Young, Desired me to ask about it. David Said, Oliver, & The Prophet, & I were riding in a wagon, and an aged man about 5 feet 10 heavey Set & on his back an old fashioned Armey knapsack Straped over his Shoulders & Something Square in it, & he walked alongside of the Wagon & Wiped the Sweat off his face, Smileing very Pleasant David asked him to ride and he replied I am going across to the hill Cumorah (“Edward Stevenson Interview (1) 22-23 December 1877, Richmond, Missouri Diary of Edward Stevenson,” LDS Church Archives, Lyndon W. Cook, ed., David Whitmer Interviews, 1993, p. 13; also Dan Vogel, ed., Early Mormon Documents, 2003, vol. v, p. 30).