Worry always muffles the voice of Jesus, making it easy to misunderstand what he is trying to say to us. After witnessing not one but two miraculous, multiplying feasts, the disciples are in a boat with Jesus, worrying because they forgot to bring enough bread. Jesus is trying to warn them about the influence of the Pharisees and Herod, using yeast as a metaphor, but the disciples completely misunderstand him: “It is because we have no bread,” the assume.
The disciples’ constant worry about having enough bread to eat reveals their lack of faith in God’s provision, even after Jesus fed multitudes twice. It’s almost as if they didn’t recognize that a miracle had occurred. Their worry prevented them from seeing the miracle of provision, and from hearing what Jesus was really saying to them.