Whereof the Holy Ghost also is a witness to us. Hebrews 10:15
And it came to pass after I, Nephi, having heard all the words of my father, concerning the things which he saw in a vision, and also the things which he spake by the power of the Holy Ghost, which power he received by faith on the Son of God – and the Son of God was the Messiah who should come – I, Nephi, was desirous also that I might see, and hear, and know of these things, by the power of the Holy Ghost, which is the gift of God unto all those who diligently seek him, as well in times of old as in the time that he should manifest himself unto the children of men.
And the Holy Ghost giveth authority that I should speak these things, and deny them not. Book of Mormon: I Nephi 10:17&22
And blessed are they who shall seek to bring forth my Zion at that day, for they shall have the gift and the power of the Holy Ghost; and if they endure unto the end they shall be lifted up at the last day, and shall be saved in the everlasting kingdom of the Lamb; and whoso shall publish peace, yea, tidings of great joy, how beautiful upon the mountains shall they be. Book of Mormon: I Nephi 13:37
And Alma went forth, and also Amulek, among the people, to declare the words of God unto them; and they were filled with the Holy Ghost. Book of Mormon: Alma 8:30
Know ye not, my son, that these things are an abomination in the sight of the Lord; yea, most abominable above all sins save it be the shedding of innocent blood or denying the Holy Ghost?
For behold, if ye deny the Holy Ghost when it once has had place in you, and ye know that ye deny it, behold, this is a sin which is unpardonable; yea, and whosoever murdereth against the light and knowledge of God, it is not easy for him to obtain forgiveness; yea, I say unto you, my son, that it is not easy for him to obtain a forgiveness. Book of Mormon: Alma 39:5&6
It came to pass when they were all baptized and had come up out of the water, the Holy Ghost did fall upon them, and they were filled with the Holy Ghost and with fire. Book of Mormon: III Nephi 19:13
And the Holy Ghost beareth record of the Father and me; and the Father giveth the Holy Ghost unto the children of men, because of me. Book of Mormon: III Nephi 28:11