Doctrine & Covenants 1:17-29

Wherefore, I the Lord, knowing the calamity which should come upon the inhabitants of the earth, called upon my servant Joseph Smith, Jun., and spake unto him from heaven, and gave him commandments; and also gave commandments to others, that they should proclaim these things unto the world; and all this that it might be fulfilled, which was written by the prophets . . . And after having received the record of the Nephites, yea, even my servant Joseph Smith, Jun., might have power to translate through the mercy of God, by the power of God, the Book of Mormon."