Prophet Brigham Young is quoted in LDS Scripture as saying that those in interracial marriages with African people should be “put to death”. Here is a quote directly from Brigham Young giving a sermon to LDS people about the African race which he considered to be the descendants of Cain:
“Shall I tell you the law of God in regard to the African race? If the white man who belongs to the chosen seed mixes his blood with the seed of Cain, the penalty, under the law of God, is death on the spot. This will always be so. The nations of the earth have transgressed every law that God has given, they have changed the ordinances and broken every covenant made with the fathers, and they are like a hungry man that dreameth that he eateth, and he awaketh and behold he is empty.”
– Prophet Brigham Young, Journal of Discourses, v. 10, p. 110 (March 8, 1863)
You can find the Journal of Discourses, where this quote comes from, still referenced as scripture, in the LDS church’s official university resources: http://scriptures.byu.edu/
This quote also goes along with Brigham Young’s preaching on Blood Atonment, where he says there are some sins that cannot be covered by Christ’s atonement, and must instead be covered by shedding of the sinner’s blood. Having a child with a black person is one of the sins that Brigham Young categorizes as such.
The Journal of Discourses has been considered LDS scripture for many years, and is still sold in the LDS book store.
For more information about what is considered mormon scripture, please see:
All these facts can be verified via the inline links above.