Mark 14:27-31 - Known failure
Here we see yet another prophecy from the Old Testament part of the Bible (written 500 years before Jesus came)... 'I will strike the shepherd and the sheep will be scattered.' (Zechariah 13:7). Jesus repeatedly said he was 'the good shepherd' (John 10:11, 14) and Isaiah (written 700 years before Jesus came) said that he would be 'stricken' by God (Isaiah 53:4) and that it would be God's will to 'crush him' (Isaiah 53:10). Jesus is again describing how another prophecy would be fulfilled. He knows his friends will all desert him in his time of greatest need, according to what God had said through the prophets hundreds of years before.
Peter claims he will remain true to Jesus, even if no-one else does but Jesus knows better and even describes the exact details of how Peter will fail. And it happens just as he says (Mark 14:66-72).
Jesus knows us better than we know ourselves. He knows we will fail him and he knows how. The good news is, this is not the end of the story. Jesus is on his way to his death and our failure is the reason why. He knows us. He knows our failure. And he knows what it will cost him to make a way out for us.