D&C 17

Can you imagine the thrill these three bethren, Oliver Cowdery, David Whitmer, and Martin Harris must have felt as the Lord revealed -

"...I say unto you, that you must rely upon my word, which if you do with full purpose of heart, you shall have a view of the plates, and also of the breastplate, the sword of Laban, the Urim and Thummim, which were given to the brother of Jared upon the mount, when he talked with the Lord face to face, and the miraculous directors which were given to Lehi while in the wilderness, on the borders of the Red Sea." (Doctrine and Covenants Section 17:1)

All three had somewhat pressured the Prophet to be witnesses, as they learned from the sacred record as Moroni wrote to the Prophet -

"...behold, ye may be privileged that ye may show the plates unto those who shall assist to bring forth this work;
3 And unto three shall they be shown by the power of God; wherefore they shall know of a surety that these things are true.
4 And in the mouth of three witnesses shall these things be established; and the testimony of three, and this work, in the which shall be shown forth the power of God and also his word, of which the Father, and the Son, and the Holy Ghost bear record—and all this shall stand as a testimony against the world at the last day." (Book of Mormon Ether 5:2 - 4)

Moroni stressed that it would be shown to three "by the power of God". The Lord also revealed to the three to-be witnesses -

"ye shall testify that you have seen them, even as my servant Joseph Smith, Jun., has seen them; for it is by my power that he has seen them, and it is because he had faith." (Doctrine and Covenants Section 17:5)

Therefore -

"...you have received the same power, and the same faith, and the same gift like unto him..." (Doctrine and Covenants Section 17:7)

This event did happen by faith and by the power of God. The Prophet records -

“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 by vocal 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 withdrew 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 thereon 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.’” (History of the Church, 1:54–55.)

The Prophet then records -

“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, 1:55.)

Their testimony given faith and the power of God are included in every published Book of Mormon.