Charles Ellicott Commentary Mark 8:31-33

"And he began to teach them, that the Son of man must suffer many things, and be rejected by the elders, and the chief priests, and the scribes, and be killed, and after three days rise again. And he spake the saying openly. And Peter took him, and began to rebuke him. But he turning about, and seeing his disciples, rebuked Peter, and saith, Get thee behind me, Satan; for thou mindest not the things of God, but the things of men." — Mark 8:31-33 (ASV)

And he began to teach them.—See Notes on Matthew 16:21-23.

The points peculiar to St. Mark are:

1. that our Lord spoke that saying openly—the absence of any reticence in this announcement of apparent failure was what startled the disciples;
2. and the graphic touch that as He rebuked Peter, He turned and looked, not on that Apostle only, but on the whole company of the disciples.