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Source:Martin Harris:Metcalfe:Ten Years Before the Mast:EMD 2:346-347:While praying I passed into a state of entrancement
Martin Harris (1873-1874): "While praying I passed into a state of entrancement, and in that state I saw the angel and the plates"
Anthony Metcalf interviewed Martin Harris in the 1873 or 1874 timeframe. Note that Metcalf considered Joseph Smith a "pretended prophet" and was therefore relating Harris's claims from a skeptical perspective:
Following is the history as related to me, including all his connections with Joseph Smith, the pretended prophet and the founder of the Mormon church: He told me all about the translating of the Book of Mormon, and said he had give $5,000 towards its publication. He said "I never saw the golden plates, only in a visionary or entranced state. I wrote a great deal of the Book of Mormon myself, as Joseph Smith translated or spelled the words out in English. Sometimes the plates would be on a table in the room in which Smith did the translating, covered over with cloth. I was told by Joseph Smith that God would strike him dead if he attempted to look at them, and I believed it. When the time came for the three witnesses to see the plates, Joseph Smith, myself, David Whitmer and Oliver Cowdery, went into the woods to pray. When they had all engaged in prayer, they failed at that time to see the plates or the angel who should have been on hand to exhibit them. They all believed it was because I was not good enough, or, in other words, not sufficiently sanctified. I withdrew. As soon as I had gone away, the three others saw the angel and the plates. In about three days I went into the woods to pray that I might see the plates. While praying I passed into a state of entrancement, and in that state I saw the angel and the plates." 
- "Martin Harris Interview with Anthony Metcalf, Circa 1873-1874," in Vogel (ed.) Early Mormon Documents 2:346-347.