Matthew 16:1 introduces the very Pharisees and Sadducees Jesus warns about in 16:11 — their testing prompts his caution about their corrupting influence.

In Matthew 15:16, Jesus rebukes the disciples' lack of understanding with the same frustration — both passages highlight their spiritual dullness despite being with him.

In Matthew 3:7, John the Baptist condemns the same group (Pharisees and Sadducees) as a 'brood of vipers', paralleling Jesus' warning about their corrupting influence.

In Matthew 13:51, Jesus similarly tests his disciples' understanding after parables — here they claim to understand, but in 16:11 they fail to grasp the leaven metaphor.

In Matthew 22:16, the Pharisees again try to ensnare Jesus, illustrating the dangerous influence (leaven) he warned against in 16:11.

Mark 8:21 is the parallel account — Jesus asks 'Do you not yet understand?' about the leaven of the Pharisees.

Leviticus 2:11 bans leaven from grain offerings, providing the OT background for leaven as a symbol of corruption.

Mark 8:15 records the same warning about leaven of the Pharisees (and Herod), directly paralleling Matthew 16:11 — the disciples' misunderstanding is explained.

In Mark 7:18, Jesus similarly rebukes the disciples for failing to understand a teaching metaphor — a recurring pattern of their dullness seen also in Matthew 16:11.