In the New Testament, Jesus foretold his death and resurrection in a number of passages. In Mark 8:30-33, it relates how the apostle Peter—one of the closest apostles to Jesus—confronted and reprimanded Him for such ‘negative speech.’
Peter and the gospel writers later proclaimed Jesus was God. Suffice it to say, Peter telling the Son of an God that He doesn’t know what He’s talking about is pretty embarrassing (not to mention foolish).
It’s not likely Mark would have invented a story about Peter admonishing the Son of God.