This is one of the passages that led to the testimony of the three witnesses published with the Book of Mormon.
"In the course of the work of translation, we ascertained that three special witnesses were to be provided by the Lord, to whom He would grant that they should see the plates from which this work (the Book of Mormon) should be translated; and that these witnesses should bear record of the same, as will be found recorded, Book of Mormon, page 581 [Book of Ether, chapter 5, verses 2, 3 and 4, p. 487, edition 1920], also page 86 [2 Nephi, chapter 11, verse 3, p. 73, edition 1920]. fn Almost immediately after we had made this discovery, it occurred to Oliver Cowdery, David Whitmer and the aforementioned Martin Harris (who had come to inquire after our progress in the work) that they would have me inquire of the Lord to know if they might not obtain of him the privilege to be these three special witnesses; and finally they became so very solicitous, and urged me so much to inquire that at length I complied; and through the Urim and Thummim, I obtained of the Lord for them the following: (DC 17)
Not many days after the above commandment was given, we four, viz., Martin Harris, David Whitmer, Oliver Cowdery and myself, agreed to retire into the woods, and try to obtain, by fervent and humble prayer, the fulfilment of the promises given in the above revelation—that they should have a view of the plates. We accordingly made choice of a piece of woods convenient to Mr. Whitmer’s house, to which we retired, and having knelt down, we began to pray in much faith to Almighty God to bestow upon us a realization of these promises.
According to previous arrangement, I commenced prayer to our Heavenly Father, and was followed by each of the others in succession. We did not at the first trial, however, obtain any answer or manifestation of divine favor in our behalf. We again observed the same order of prayer, each calling on and praying fervently to God in rotation, but with the same result as before.
Upon this, our second failure, Martin Harris proposed that he should withdraw himself from us, believing, as he expressed himself, that his presence was the cause of our not obtaining what we wished for. He accordingly with drew from us, and we knelt down again, and had not been many minutes engaged in prayer, when presently we beheld a light above us in the air, of exceeding brightness; and behold, an angel stood before us. In his hands he held the plates which we had been praying for these to have a view of. He turned over the leaves one by one, so that we could see them, and discern the engravings theron distinctly. He then addressed himself to David Whitmer, and said, “David, blessed is the Lord, and he that keeps His commandments;” when, immediately afterwards, we heard a voice from out of the bright light above us, saying, “These plates have been revealed by the power of God, and they have been translated by the power of God. The translation of them which you have seen is correct, and I command you to bear record of what you now see and hear.”
I now left David and Oliver, and went in pursuit of Martin Harris, whom I found at a considerable distance, fervently engaged in prayer. He soon told me, however, that he had not yet prevailed with the Lord, and earnestly requested me to join him in prayer, that he also might realize the same blessings which we had just received. We accordingly joined in prayer, and ultimately obtained our desires, for before we had yet finished, the same vision was opened to our view, at least it was again opened to me, and I once more beheld and heard the same things; whilst at the same moment, Martin Harris cried out, apparently in an ecstasy of joy, “ ’Tis enough; ’tis enough; mine eyes have beheld; mine eyes have beheld;” and jumping up, he shouted, “Hosanna,” blessing God, and otherwise rejoiced exceedingly." (History of the Church Volume 1, p. 52 - 53).
“In the first edition of the Book of Mormon the testimony of Three Witnesses, and also the Testimony of Eight Witnesses appear at the end—or on the last two pages of the volume, instead of being, as in the later editions, on the page following the title-page.” (History of the Church Volume 1, Footnotes)