Great crowds have flocked to Jesus in the region of the Decapolis, on the east side of the Sea of Galilee. They have come to hear him and to be healed, bringing along large baskets, or hampers, of provisions.

In time, however, Jesus tells his disciples: “I feel pity for the crowd, because they have already stayed with me for three days and they have nothing to eat. If I send them off to their homes hungry, they will give out on the road, and some of them are from far away.” The disciples ask: “From where will anyone get enough bread in this isolated place to satisfy these people?”​—Mark 8:2-4.

Jesus responds: “How many loaves do you have?” The disciples say: “Seven, and a few small fish.” (Matthew 15:34) Then Jesus has the people recline on the ground. He takes the loaves and the fish, prays to God, and gives them to his disciples to distribute. Amazingly, all eat to satisfaction. The leftovers collected fill seven large provision baskets, even though about 4,000 men, as well as women and children, have eaten!

After Jesus sends the crowds away, he and the disciples cross by boat to Magadan, on the western shore of the Sea of Galilee. Here, Pharisees accompanied by some of the sect of the Sadducees try to test Jesus, asking him to display a sign from heaven.

Realizing what their motives are, Jesus replies: “When evening falls, you say, ‘It will be fair weather, for the sky is fire-red,’ and in the morning, ‘It will be wintry, rainy weather today, for the sky is fire-red but gloomy.’ You know how to interpret the appearance of the sky, but the signs of the times you cannot interpret.” (Matthew 16:2, 3) Then Jesus tells the Pharisees and Sadducees that no sign will be given them except the sign of Jonah.

Jesus and his disciples get in a boat and head toward Bethsaida on the northeast shore of the sea. En route, the disciples discover that they forgot to bring enough bread. They have just one loaf. Having in mind his recent encounter with the Pharisees and the Sadducean supporters of Herod, Jesus warns: “Keep your eyes open; look out for the leaven of the Pharisees and the leaven of Herod.” The disciples mistakenly think that his mention of leaven refers to their forgetting to bring bread. Noting their mistake, Jesus says: “Why do you argue over your having no bread?”​—Mark 8:15-17.

Jesus had recently provided bread for thousands of people. So the disciples should know that he is not concerned about a lack of literal loaves. “Do you not remember,” he asks, “when I broke the five loaves for the 5,000 men, how many baskets full of fragments you collected?” They answer: “Twelve.” Continuing, Jesus says:  “When I broke the seven loaves for the 4,000 men, how many large baskets full of fragments did you take up?” They reply: “Seven.”​—Mark 8:18-20.

Jesus asks: “How is it you do not discern that I did not speak to you about bread?” He adds: “Watch out for the leaven of the Pharisees and Sadducees.”​—Matthew 16:11.

Finally, the disciples get the point. Leaven is used to cause fermentation and make bread rise. Jesus is here using leaven as a symbol of corruption. He is warning the disciples to be on guard against “the teaching of the Pharisees and Sadducees,” which has a corrupting effect.​—Matthew 16:12.