(6) Beware of the leaven of the Pharisees.--The form of the warning was obviously determined by the fact just narrated. The Master saw the perplexed looks and heard the self reproaching or mutually accusing whispers of the disciples, and made them the text of a proverb which was a concentrated parable. As St. Mark gives the words, they stand, "Beware of the leaven of the Pharisees, and of the leaven of Herod," and this, if we have to make our choice, we may believe to have been the form in which they were actually spoken; St. Matthew, or the report which he followed, substituting for the less known Herodians the better known Sadducees. The language of the tetrarch, as has been shown (see Note on Matthew 14:2), implies that Sadduceeism had been the prevailing belief of his life, and the current of Jewish political, not to say religious, sympathies, naturally led the Sadducean priests, courting (as Caiaphas did) the favour of the Roman rulers, to fraternise with the scribes who attached themselves to the party of the tetrarch. (Comp. Acts 5:17.)

Verse 6. - The leaven. Christ's thoughts were still fixed on the late disputants, whose powerful influence on popular opinion called for forcible warning. By "leaven" he does not here refer specially to the hypocrisy of the Pharisees and Sadducees, as in Luke 12:1, but to the evil influence which they exercised, which was diffused far and wide, and penetrated to all ranks and classes. Their unsound opinions, their inability or disinclination to enter into the spiritual sense of Scripture, vitiated their whole system, and made them dangerous teachers directly they attempted to explain or amplify the letter of Holy Writ. It was this same perverse blindness that led them to refuse to accept Jesus as Messiah in spite of all the proofs which had been brought before them. That leaven, in one aspect, was regarded as a sign of impurity and corruption, we learn from the strict rules which banished it from Divine service, and especially during the Passover season. Says St. Paul, "A little leaven leaveneth the whole lump" (Galatians 5:9); and, "Purge out the old leaven, that ye may be a new lump, even as ye are unleavened" (1 Corinthians 5:7). Elsewhere Christ makes a distinction between what these teachers taught ex cathedra, and what they put forth on their own authority or what they practised themselves (Matthew 23:2, 3, where see note).

16:5-12 Christ speaks of spiritual things under a similitude, and the disciples misunderstand him of carnal things. He took it ill that they should think him as thoughtful about bread as they were; that they should be so little acquainted with his way of preaching. Then understood they what he meant. Christ teaches by the Spirit of wisdom in the heart, opening the understanding to the Spirit of revelation in the word.Then Jesus said unto them,.... Either taking occasion from the disciples observing that they had forgot to take bread with them, or on account of what passed between him and the Pharisees and Sadducees, he gave the following advice to his disciples;

take heed and beware of the leaven of the Pharisees and of the Sadducees. Mark, instead "of the leaven of the Sadducees", says, "the leaven of Herod"; either because Christ might caution against all three; or because the Sadducees were generally Herodians, taking Herod to be the Messiah; or were on his party, or for his government, which the Pharisees disliked; and the Herodians were generally Sadducees. By "the leaven" of these is meant their doctrine, as appears from Matthew 16:12. The doctrines the Pharisees taught were the commandments and inventions of men, the traditions of the elders, free will, and justification by the works of the law: the doctrine of the Sadducees was, that there was no resurrection of the dead, nor angels, nor spirits: now because they sought secretly and artfully to infuse their notions into the minds of men; and which, when imbibed, spread their infection, and made men sour, morose, rigid, and ill natured, and swelled and puffed them up with pride and vanity, Christ compares them to leaven; and advises his disciples to look about them, to watch, and be on their guard, lest they should be infected with them.