The previous passage yesterday Jesus acknowledges that he is the Messiah, but here we find that Jesus refers to himself again as “Son of man.” If he wanted news of his being Messiah to remain just among them, it would make sense if he used that title when out and about, He then began to teach them that the Son of Man must suffer many things and be rejected by the elders, the chief priests and the teachers of the law, and that he must be killed and after three days rise again.”. “But when Jesus turned and looked at his disciples, he rebuked Peter. ‘Get behind me, Satan!’ he said. ‘You do not have in mind the concerns of God, but merely human concerns.'”

Jesus Predicts His Death it reads in Mark 8:31-33,
He then began to teach them that the Son of Man must suffer many things and be rejected by the elders, the chief priests and the teachers of the law, and that he must be killed and after three days rise again. He spoke plainly about this, and Peter took him aside and began to rebuke him. But when Jesus turned and looked at his disciples, he rebuked Peter. “Get behind me, Satan!” he said. “You do not have in mind the concerns of God, but merely human concerns.”