Another parable spake He unto them; “The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened.” Matthew 13:33
Parable
Do Not Keep Them From The Children
“Give ear, O my people, to my law: incline your ears to the words of my mouth.
I will open my mouth in a parable: I will utter dark sayings of old: which we have heard and known, and our fathers have told us.
We will not hide them from their children, shewing to the generation to come the praises of the LORD, and His strength, and His wonderful works that He hath done.
For He established a testimony in Jacob, and appointed a law in Israel, which He commanded our fathers, that they should make them known to their children: that the generation to come might know them, even the children which should be born; who should arise and declare them to their children: that they might set their hope in God, and not forget the works of God, but keep His commandments: and might not be as their fathers, a stubborn and rebellious generation; a generation that set not their heart aright, and whose spirit was not stedfast with God.” Psalm 78:1-8 (KJB)
The New and the Old
“And Jesus said unto them, ‘Can the children of the bridechamber fast, while the bridegroom is with them? As long as they have the bridegroom with them, they cannot fast. But the days will come, when the bridegroom shall be taken away from them, and then shall they fast in those days.
No man also seweth a piece of new cloth on an old garment: else the new piece that filled it up taketh away from the old, and the rent is made worse. And no man putteth new wine into old bottles: else the new wine doth burst the bottles, and the wine is spilled, and the bottles will be marred: but new wine must be put into new bottles.’” Mark 2:19-22 (KJB)
From John Gills Exposition of the Bible…
No man also seweth a piece of new cloth, The traditions of the elders are meant, particularly concerning eating and drinking, and fasting, things before spoken of; and which occasioned this parable, and which were new things in comparison of the commands of God: some of them were of very short standing, devised in, that age; and most, if not all of them, were since the times of Ezra.
On an old garment; the moral and ceremonial righteousness of the Jews, in obedience to the law of God; signifying, that the former were not to be joined with these, to make up a justifying righteousness before God; which were not sufficient for such a purpose, either singly, or both together:
else the new piece that filled it up, taketh away from the old, and the rent is made worse; for by attendance to the traditions of the elders, the Jews were taken off from, and neglected the commandments of God; nay, oftentimes the commands of God were made void by these traditions, so that the old garment of their own righteousness, which was very ragged and imperfect of itself, instead of being purer and more perfect, became much the worse, even for the purpose for which it was intended; See Gill on Mat_9:16.
The Things Which Defile Humankind
“And He called the multitude, and said unto them, ‘Hear, and understand: Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth, this defileth a man. Then came His disciples, and said unto Him, ‘Knowest Thou that the Pharisees were offended, after they heard this saying?’ But He answered and said, ‘Every plant, which My heavenly Father hath not planted, shall be rooted up. Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.’ Then answered Peter and said unto Him, ‘Declare unto us this parable.’ And Jesus said, ‘Are ye also yet without understanding? Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught? But those things which proceed out of the mouth come forth from the heart; and they defile the man. For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies: these are the things which defile a man: but to eat with unwashen hands defileth not a man.’” ~Jesus (Matthew 15:10-20)
The Fire and Hammer 