Joseph Smith: Blacks Have Souls and Should Be Separate but Legally Equal (2 Jan. 1843)
Joseph Smith, History of the Church, 5:217-18
Elder Hyde inquired the situation of the negro. I replied, they came into the world slaves, mentally and physically. Change their situation with the whites, and they would be like them. They have souls, and are subjects of salvation. Go into Cincinnati or any city, and find an educated negro, who rides in his carriage, and you will see a man who has risen by the powers of his own mind to his exalted state of respectability.* The slaves in Washington are more refined than many in high places, and the black boys will take the shine off many of those they brush and wait on. Elder Hyde remarked, “Put them on the level, and they will rise above me.” I replied, if I raised you to be my equal, and then attempted to oppress you, would you not be indignant and try to rise above me, as did Oliver Cowdery, Peter Whitmer, and many others, who said I was a fallen Prophet, and they were capable of leading the people, although I never attempted to oppress them, but had always been lifting them up? Had I anything to do with  the negro, I would confine them by strict law to their own species, and put them on a national equalization.
* Probably a reference to Elijah Abel, one of the very few (perhaps only two) black Mormons who had received the priesthood during Joseph Smith’s lifetime. Abel had moved to Cincinnati in 1842. See Newell G. Bringhurst, “Elijah Abel and the Changing Status of Blacks within Mormonism,” in Neither White nor Black: Mormon Scholars Confront the Race Issue in a Universal Church, ed. Lester E. Bush Jr. and Armand L. Mauss (Midvale, UT: Signature Books, 1984), 133.