The Religious Authorities of Jesus' day arrive, demanding a miraculous sign to prove Jesus is sent by God. Jesus replies to their demand by telling his disciples to beware of them and reminds them of his two greatest miracles... feeding the 5,000 and feeding the 4,000. Today, this bad yeast exists as those who claim to speak for Jesus whose own messages sound nothing like his teaching. This is the yeast that Jesus tells us, as his disciples, we must beware of, today.
The religious authorities of Jesus' day criticize him for allowing his disciples to eat before washing their hands. Jesus response? Take a look at yourself! The words we speak are a direct reflection of the condition of our hearts. Those whose hearts are fixed upon the merciful love of God, naturally reflect that love and mercy by the ways in which they speak to others.
There are times when we ask the Lord for a challenge, and Jesus does exactly this. But, then we begin to question what we want and our ability to succeed in carrying it out, we grow afraid, uncertain, and overwhelmed. We forget that we are filled by the Spirit's power, and that the Lord is right there, ready, willing and able to stretch out his hand and save us.