TSK
Treasury of Scripture Knowledge references in ASV.
Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.
Then understood they that he bade them not beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.
In the mean time, when the many thousands of the multitude were gathered together, insomuch that they trod one upon another, he began to say unto his disciples first of all, Beware ye of the leaven of the Pharisees, which is hypocrisy.
The disciples therefore said one to another, Hath any man brought him [aught] to eat?
A little leaven leaveneth the whole lump.