“But be alert!
I have already
ὑμεῖς δὲ βλέπετε· προείρηκα ὑμῖν πάντα.
This is like Matthew, chapter 24:25. Mark said that Jesus warned his disciples to be alert (ὑμεῖς δὲ βλέπετε). He had already told them everything, before it happened (προείρηκα ὑμῖν πάντα). The disciples should be wary of these false messiahs and false prophets.