This was at a prayer meeting where the Prophet Joseph presided and Elder Brigham Young in his prayer spoke in tongues, moved upon by the Spirit of God, and when he had ceased praying the Prophet continued in the same tongue that Elder Brigham Young had spoken in, and as he closed his remarks, he said, "My brethren and sisters, the tongue that Brother Brgham spoke in, and I have continued in, is the pure Adamic language spoken by our father Adam," and it is from the Lord. Elder Seymour B. Young, Conference Report, October 1922, Third Day—Morning Session, p.145 - 146
That is perfectly natural; for when that which is perfect is come, we shall see as we are seen, and know as we are known. There will be no need for men to prophesy what shall take place, for we shall all see and understand it. In that day it will not be necessary for one to say to another, Know ye the Lord; for all shall know Him. Perfect knowledge will be enjoyed by all. We shall see eye to eye, and be of one heart and mind in the kingdom of God. It will not be necessary for any to speak in an unknown tongue; for the original Adamic language will be restored, and all shall speak in the one tongue. Hence how consistent it is to say, "When that which is perfect is come, then that which is in part shall be done away." These gifts are now given to us as a lamp to lighten our pathway, to encourage us when our spirits are drooping, to heal our bodies when we are afflicted, and to give us knowledge of things to come, that we may be buoyed up and go on to perfection. (Elder John W. Taylor, Conference Report, October 1903, Overflow Meeting, p.97)
Bruce R. McConkie, Mormon Doctrine, 2d ed., p.19 During the millennium, it appears that men will again have power to speak and write the Adamic language. Of that day the Lord says he will "turn to the people a pure language, that they may all call upon the name of the Lord, to serve him with one consent." (Zeph. 3:9.) In some instances when the saints speak in tongues, the language impressed upon them by the power of the Spirit is the pure Adamic tongue.
Mother Whitney was baptized in November, 1830, and from that time to her death was a faithful and devoted member of the Church. In its early days she was designated by the Prophet Joseph Smith as "the sweet songstress of Zion." She was among the first members of the Church to receive the gift of tongues, which she always exercised in singing. The Prophet said that the language was the pure Adamic tongue, the same that was used in the garden of Eden, and he promised that if she kept the faith, the gift would never leave her. It never did, and many who heard her sing never forgot the sweet and holy influence that accompanied her exercise of this heavenly gift. The [p.564] last time she sang in tongues was on the day she was 81 years old. LDS Biographical Encyclopedia, Andrew Jenson, Vol. 3, p.563
The Adamic tongue was a powerful language that communicated not only words and ideas but also the power of God. "And so great was the faith of Enoch that he led the people of God, and their enemies came to battle against them; and he spake the word of the Lord, and the earth trembled, and the mountains fled, even according to his command; and the rivers of water were turned out of their course; and the roar of the lions was heard out of the wilderness; and all nations feared greatly, so powerful was the word of Enoch, and so great was the power of the language which God had given him" (Moses 7:13). Moroni seems in awe of the power of this language, as contained in the writings of the brother of Jared: "And thou hast made us [the Nephites] that we could write but little, because of the awkwardness of our hands. Behold, thou hast not made us mighty in writing like unto the brother of Jared, for thou madest him that the things which he wrote were mighty even as thou art, unto the overpowering of man to read them" (Ether 12:24). Robert L. Millet, Alive in Christ: The Miracle of Spiritual Rebirth, p.130 - 131