Mark 9:33-35

33Jesus and his disciples arrived at Capernaum. When they were in the house, Jesus asked them, ‘What were you arguing about on the way?’

34But they did not say anything. They did not want to tell Jesus why they were arguing. On the way, they had argued about who was the most important disciple.

35Jesus sat down. He told the 12 apostles to come to him. Then he said to them, ‘If you want to be the leader, make yourself less important than everyone else. You must become the servant of everyone.’