Matthew 16:10 Meaning

8Which when Jesus perceived, he said unto them, O ye of little faith, why reason ye among yourselves, because ye have brought no bread?

9Do ye not yet understand, neither remember the five loaves of the five thousand, and how many baskets ye took up?

10Neither the seven loaves of the four thousand, and how many baskets ye took up?

11How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?

12Then understood they how that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees.