The Pharisees and Sadducees tested Jesus by asking him for a sign. They were not genuinely seeking to know Jesus. Their intent was to find a way to discredit Jesus.

Jesus knew their malicious intent. Jesus had already given many signs about himself through his miracles and his teaching. He rebuked them, for they could understand the weather from signs in the sky, but they failed to interpret the miraculous signs he had given to them. Jesus called them a wicked and adulterous generation for asking for another sign. But as he had previously done, Jesus gave them the sign of Jonah (12:38-40). Jesus’ resurrection from the dead on the third day is his greatest sign, revealing him to be the Messiah.

Jesus took this encounter with the Pharisees and Sadducees to teach his disciples. He warned them to guard against their yeast. The disciples mistakenly understood Jesus to mean bread, but Jesus meant the teaching of the Pharisees and Sadducees. Their self-centered, legalistic, and hypocritical teaching looked small, like yeast. But if the disciples were not careful, they would become just like the religious officials. Likewise, we must guard our hearts by humbly studying the Bible and grow in love for God and for others.
Application: Father, thank you for the pure gospel. Please guard my heart against yeast.
One Word: Guard your heart