"Get on your knees you f**king slave."
That's only part of an insanely racist and disturbing message NFL star Budda Baker says he received after his game Sunday ... and the text to the Arizona Cardinals player was absolutely vile.
Baker received the message apparently as a response for his low hit on SF star George Kittle over the weekend ... and it was so awful, Baker wrote of it, "All you can do is pray for ppl like this."
In the message, which Baker shared publicly on social media, a fan with the username "niners8" called the NFL safety a "monkey" and directed the n-word at him 3 times.