The phrase "the leaven of the Pharisees and of Herod" is a metaphorical expression used by Jesus Christ to caution His disciples against the corrupting influence of certain teachings and behaviors. This expression is found in the New Testament, specifically in the Gospel of Mark and the Gospel of Matthew.

Biblical References:

1. Mark 8:15 : "‘Watch out!’ He cautioned them. ‘Beware of the leaven of the Pharisees and of Herod.’"
2. Matthew 16:6 : "‘Watch out!’ Jesus told them. ‘Beware of the leaven of the Pharisees and Sadducees.’"

Context and Interpretation:

In the context of Mark 8:15, Jesus had just performed the miracle of feeding the four thousand with seven loaves and a few small fish. Afterward, the Pharisees approached Him, demanding a sign from heaven to test Him. Jesus, aware of their hardened hearts and unbelief, refused to give them a sign and departed with His disciples. It is during this journey across the lake that Jesus warns His disciples about the "leaven of the Pharisees and of Herod."

The term "leaven" in biblical times was commonly understood as a symbol of influence, often with a negative connotation. Leaven, or yeast, is a small substance that ferments and causes dough to rise, symbolizing how a small amount of influence can permeate and transform an entire entity. In this context, Jesus uses "leaven" to describe the pervasive and corrupting influence of the Pharisees and Herod.

The Pharisees:

The Pharisees were a religious group known for their strict adherence to the Law of Moses and the traditions of the elders. They were often criticized by Jesus for their hypocrisy, legalism, and self-righteousness. The "leaven of the Pharisees" refers to their tendency to focus on external religious observance while neglecting the weightier matters of the law, such as justice, mercy, and faithfulness (Matthew 23:23). Their influence was marked by a spirit of pride, hypocrisy, and a lack of genuine faith.

Herod:

Herod, likely referring to Herod Antipas, was the tetrarch of Galilee and Perea during Jesus' ministry. Known for his political cunning and moral corruption, Herod represents the secular and political power that often opposed the message of the Kingdom of God. The "leaven of Herod" can be understood as the influence of worldly power, ambition, and moral compromise. Herod's life was characterized by a pursuit of pleasure, political expediency, and a disregard for righteousness, as evidenced by his unlawful marriage to Herodias and the execution of John the Baptist (Mark 6:17-29).

Application:

Jesus' warning to "beware of the leaven of the Pharisees and of Herod" serves as a timeless admonition for believers to guard against the subtle and pervasive influences of legalism, hypocrisy, and worldliness. It calls for discernment and vigilance in maintaining the purity of faith and devotion to God. The disciples, initially misunderstanding Jesus' metaphor, were reminded of the importance of spiritual insight and reliance on divine truth rather than human traditions or political power.

In summary, the "leaven of the Pharisees and of Herod" encapsulates the dangers of allowing corrupting influences to infiltrate one's faith and life, urging believers to remain steadfast in their commitment to the teachings of Christ and the values of the Kingdom of God.