Brigham says that he has not checked the Scriptures to see if his revelations are consistent with them; when he speaks by the power of God and the Holy Ghost, it is "truth" and "scripture."
"Discourse by Prest. Brigham Young, At Logan, Cache County, on Monday, May 25, 1877, at the Priesthood Meeting, held for the purpose of organizing a Stake of Zion," Deseret News, 26 no. 18 (June 6, 1877): 270
In my doctrinal teachings I have taught many things not written in any book, ancient or modern, and yet, notwithstanding these things, I have told the people, I have never looked into the Bible, the Book of Mormon, or the Doctrine and Covenants, or any of our church works to see whether they agreed with them or not.
When I have spoken by the power of God and the Holy Ghost, it is truth, it is scripture, and I have no fears but that it will agree with all that has been revealed in every particular.