Mark 8:30
Jesus warned them not to tell anyone about him — the Messianic Secret command is applied to Peter's correct confession: no one is to be told. The reason is that the confession you are the Messiah without the passion predictions that follow is incomplete and potentially misleading — the crowd's messianic expectations would lead them to expect a political deliverer, not a suffering servant. The full disclosure of who Jesus is must wait until the cross and resurrection clarify what Messiah means.