At this point in His life, Christ begins to encounter greater and greater opposition from the religious leaders in Jerusalem. The Pharisees and Sadducees who ask Him for a sign in Matthew 16:1–4 are likely a delegation from Jerusalem sent to spy on Jesus. These two groups are usually at odds, but they can easily set aside their theological differences when they meet a common foe, just as they earlier did with John the Baptist (3:7). Matthew 15:39 locates Jesus’ meeting with these religious leaders in Magadan, west of the Sea of Galilee. The conversation with His disciples in 16:5–12 occurs on the eastern shore, or “other side” of the water. His clash with the Jerusalem officials and feeding of the four thousand (15:32–16:4) sets the stage for His warning: “Beware of the leaven of the Pharisees and Sadducees” (16:6). The disciples are perplexed, thinking that Jesus has told them not to eat bread made by these authorities. His remark makes no sense to them as they have no bread with them and do not know how they will find food to eat (v. 7). Our Savior rebukes His followers for lacking understanding and faith. After all, how could they not trust Him to feed them after seeing Him feed thousands with meager supplies (vv. 8–10)? Even so, Christ’s warning is not about food; He is speaking of the teaching of the Pharisees and the Sadducees (vv. 11–12). Jesus does use leaven as a metaphor for the growth of God’s kingdom (13:33), but in Matthew 16 He adapts Scripture’s more common negative use of leaven (Ex. 13:3; 1 Cor. 5:6–8). He is warning His followers not to embrace the Pharisees and Sadducees’ view that the Messiah must live up to their false expectations and do miracles on demand. Otherwise, like leaven, this error will penetrate their souls and turn them against the Christ. We do well to heed the words of the church father Jerome: “Leaven has this power, that, if mixed with flour, that which seemed small would grow into something larger and draw to its own essence the whole loaf. So too with heretical doctrine, if it tosses even a tiny spark into your heart, in a short time a huge flame grows beneath and draws to itself a person’s entire substance” (Commentary on Matthew 2.16.6).