“Jesus said to them.

‘Watch out!

Beware of the yeast

Of the Pharisees

And Sadducees.’”

ὁ δὲ Ἰησοῦς εἶπεν αὐτοῖς Ὁρᾶτε καὶ προσέχετε ἀπὸ τῆς ζύμης τῶν Φαρισαίων καὶ Σαδδουκαίων.

Now this saying about the yeast of the Pharisees and Sadducees can be found in Mark, chapter 8:15, and Luke, chapter 12:1, but there are slight differences.  Mark and Luke did not mention the Sadducees.  Jesus told his disciples (ὁ δὲ Ἰησοῦς εἶπεν αὐτοῖς) to watch out for and be aware (Ὁρᾶτε καὶ προσέχετε) of the yeast (ἀπὸ τῆς ζύμης) of the Pharisees and Sadducees (ἀπὸ τῆς ζύμης).  Matthew has this as a clear rebuff of both these groups and their growing yeast, leaven, or power that was expanding.  Like earlier in this chapter, there was no mention of the Scribes.  The Pharisees were a political party, a social movement, and a religious school of thought that followed the Law of Moses, but with a number of oral traditions.  They had they own expert explanations of Jewish law that sometimes appeared to be hypocritical or arrogant, with a form of Judaism that extended beyond the Temple.  The Sadducees, on the other hand, were generally aristocratic priestly officials, tied to the Temple and ritual purifications.  They were less concerned about oral traditions, so that they might have been political religious rivals to the Pharisees.  However, Jesus warned his disciples against both groups.