Just for documentation, can you tell me where God did that?
Here are a few links on the subject. They should get you started.
Topic Definition - Priesthood Ordination Before 1978
Revelation on Priesthood Accepted, Church Officers Sustained
>Just for documentation, can you tell me where God did that?
I don’t think that there is LDS scriptural documentation (meaning Bible, Book of Mormon, D&C or PofGP) on blacks not being able to receive the priesthood.
It is true that it was a common belief among Christian churches in the 1800s that blacks were descendants from Cain, and were prohibited from receiving all the blessings of God. Brigham Young seems to have followed this viewpoint as well.
And the other Christian denominations used this viewpoint to justify denying blacks the right to be baptized, receive the sacrament, worship in their churches, and to be subject to slavery.
The sole discrimination by the LDS Church against blacks was regarding the priesthood. Of course, blacks were unable to receive the priesthood according to the Old Testament as well.