30 Jesus warned them not to tell anyone about him.
References for Mark 8:30

Jesus Predicts His Death

31 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.
References for Mark 8:31
32 He spoke plainly about this, and Peter took him aside and began to rebuke him.
References for Mark 8:32
33 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.”
References for Mark 8:33
34 Then he called the crowd to him along with his disciples and said: “Whoever wants to be my disciple must deny themselves and take up their cross and follow me.
References for Mark 8:34
35 For whoever wants to save their lifeawill lose it, but whoever loses their life for me and for the gospel will save it.
References for Mark 8:35
    • ~ 8:35 - The Greek word means either "life" or "soul" ; also in verses 36 and 37.
      36 What good is it for someone to gain the whole world, yet forfeit their soul?
      37 Or what can anyone give in exchange for their soul?
      38 If anyone is ashamed of me and my words in this adulterous and sinful generation, the Son of Man will be ashamed of them when he comes in his Father’s glory with the holy angels.”
      References for Mark 8:38