Then they understood that he did not tell them to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.
12. Then they understood. The word leaven is very evidently used by Christ as contrasted with the pure and uncorrupted word of God. In a former passage, (Matthew 13:33,) Christ had used the word in a good sense, when he said that the Gospel resembled leaven; See page 127 of this volume.
Christ speaks of spiritual things in earthly pictures, and His disciples hear only bread and butter. They forgot provisions because their minds were filled with better things, which is no small mercy. But mark this: the leaven of the Pharisees, their corrupt principles spreading like yeast through dough, is far more dangerous than an empty pantry, and disciples stand most in peril from hypocrites who cloak their poison in piety.
AI summary
Commenting on Matthew 16:5-12
Then understood they,.... Without any further explication of his sense and meaning, how that he bade them not beware of the leaven of bread: which sense they first took him in; imagining, because the Pharisees were very particular and precise what sort of leaven they made use of (z), that Christ forbad them buying bread that was made with leaven according to their directions: and...