“The disciples” of Good News Translation translates they of the Greek text. It is important that the subject be specified here, for the same reason discussed in Matthew 16.7 (see comments there).

The leaven of bread is translated “the yeast used in bread” by Good News Translation. The expression may also be rendered “the yeast that one puts in bread” or, if there is a firm distinction between “bread” (cooked dough) and “dough” (uncooked bread), then a further adjustment may be made: “the yeast which one places in dough (to make it rise).”

For some languages a reversal of sentence order, placing the negative sentence last, may be more natural: “Then the disciples understood that he was referring to the teaching of the Pharisees and Sadducees. He was not warning them to guard themselves from the yeast used in bread.” Other possibilities are “Then the disciples understood that when Jesus told them to watch out for the leaven of the Pharisees and Sadducees, he didn’t mean the leaven used in making bread (or, leaven that makes bread dough rise). He meant the teaching of the Pharisees and Sadducees” and “Then the disciples realized that he was warning them about the teaching of the Pharisees and Sadducees, which was like (or, which had a spoiling effect like) yeast in bread dough.”

There will be readers who will find even these sentences difficult, particularly if in the translation the fermenting or spoiling effect of yeast has not been made clear enough. If translators are not able to convey this notion of “spoiling” in the word or phrase used for leaven, then it may be necessary here to have a very explicit simile such as “teaching that spoils (others) like leaven causes bread dough to ferment.”

The teaching of the Pharisees and Sadducees is what they taught, not what was taught to them, and some translators will have to make that explicit.

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .