Matt 15: What penalty for not washing hands?

According to the rabbinical interpretation of Ex. 34:27,34 (and others) God gave to Moses other laws and maxims orally, as well as verbal explanations of the written law, enjoining him not to record these teachings, but to deliver them to the people by word of mouth. Most modern Jewish traditions descend from the Pharisees with the notable exception of Karaite Judaism. There were many Jewish sects at the time of Christ with the main branches being Sadducee, Pharisees, Essene and Zealot. A close examination of Jesus's teachings would place him somewhere between the Pharisee and Essene with an apocalyptic emphasis -- or maybe the Gandi of the Zealot movement, where he would agree with their apocalyptic beliefs while abhorring their violent tendencies.

According to the Gospels, he upbraided the Pharisees for their oral traditions and even went so far as to say their oral law was a rejection, breaking or voiding of the written law. As Christianity and rabbinical Judaism shaped each other during the first few centuries of the common era, the rabbinical interpretations of the oral law eventually came to be written down, in spite of the fact that during Second Temple Judaism many Pharisees believed it was against God's law for them to be put into writing.

Ritual hand-washing is from these "added" laws from the oral tradition. Using asmachta, (a Biblical hint, rather than an explicit requirement) the Talmud used the requirement of washing the hands in Leviticus 15:11 as a hint for hand-washing in general. Leviticus 15:11 only speaks about washing the hands after they have been in contact with an issue of bodily fluid and the only penalty or punishment mentioned is being considered ritually impure until sundown. Ritual purity was important to many Jews to the extent of breaking the second commandment which we often call the Golden Rule. This is the reason Jesus praises the actions of a Samaritan to implicate the priest and Levite (same thing, two different people and never mind that most Second Temple Levitical priests were Sadducee, not Pharisee) who would not show compassion for the victim of the robbery who was lying bleeding on the side of the road in the parable, because his blood would have make them ritually unclean.

So, other than social ostracism, the disgust and disdain of the Pharisees and being temporarily barred from attendance at the Temple, there is no recorded punishment or penalty to be meted out for the offense.

One explanation is that the custom of washing ones hands before eating was derived from the commandment given to Aaron and his sons:

The LORD said to Moses, “You shall also make a laver of bronze, with its base of bronze, for washing. And you shall put it between the tent of meeting and the altar, and you shall put water in it, with which Aaron and his sons shall wash their hands and their feet. When they go into the tent of meeting, or when they come near the altar to minister, to burn an offering by fire to the LORD, they shall wash with water, lest they die. They shall wash their hands and their feet, lest they die: it shall be a statute for ever to them, even to him and to his descendants throughout their generations” (Exodus 30:17-21)

Whereas the commandment was given to Aaron, his sons and his descendants, the Pharisees had extrapolated it to apply to all Jews. In his commentary on Matthew, Lawrence Farley, an Eastern Orthodox writer, explains:

The hand-washing had nothing to do with hygiene, but was purely a ceremonial matter. The Law mandated that priests had to wash their hands before offering sacrifice (Ex. 30:19), and the Pharisaical custom (which was increasingly popular) was for all people to wash their hands before eating any food, whether sacrificial or not. This would, they reasoned, wash away any ceremonial defilement they may have contracted. The scribes considered this to be part of the oral law going back to Moses himself, and was called the tradition of the elders.^*

As far as I know, there wasn't any specific punishment prescribed for not following the original ordinance given in Exodus. The text simply says that they must do what they are commanded lest they die. The same sort of admonition can be found in Exodus 28:35 relating to the wearing of the robe of ephod.

^{* The Gospel of Matthew: A Torah for the Church, p.206}

The Pharisees are speaking here of the oral tradition (the Talmud and the Kabbalah before it was written), they believe that when Moses decend from Mount Sinai bring the ten commanments (written tradition), but also an oral teaching which passed to Joshua and the elders, then the prophets and so on (Robert Goldberg, Talmud, Back to the Sources: Reading the Classic Jewish Texts (New York: Simon and Schuster, 1984), p. 130).

All they are doing is adding commandments to the Torah

We have explained long ago, that the washing and bathing of the hands are derived from the words of the scribes. (Hilchoth Mikvaoth, xi. 1.)

Rebelling against God and God's word

Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the LORD your God which I command you. (Deuteronomy 4:2 AV)

What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it. (Deuteronomy 12:32 AV)

The penalty or punishment of breaking this traditions could be excommunication

It is necessary to be very careful in washing of hands, for every one who despises the washing of hands is guilty of excommunication. (Orach Chaiim., 158.)

A case actually occurred of an excommunication, and who dying in his excommunication had the usual indignities offered to his corpse

Whom did they excommunicate ? Eleazar ben Chatzar, who despised the washing of hands ; and when he was dead, the tribunal sent, and had a great stone laid on his coffin, to teach thee that of everyone who is excommunicated and dies in his excommunication, the coffin is stoned by the tribunal. (Talmud, Berachoth, fol. 19, col. 1.)

Every one who despises washing of hands sinks into poverty. R. Zerika says, in the name of li. Eliezer, Every one that despises the washing of hands is rooted out of the world. (Orach Chaiim., ibid.)

Or the penalty could be even worst, because they equate the transgression of this commandment with that of gross immorality.

Every one who eats bread without washing of hands, is as guilty as if he had committed fornication.(Sotah, fol. iv.,col. 2.)

Why they do that? Because they are full of superstitions

A man must be very careful in pouring water on his hands three times for an evil spirit rests upon the hands before washing, and does not depart until water be poured on them three times. Therefore it is necessary, before washing, to abstain from touching the hand to the mouth, and the nose, and the ears, and the eyes, because an evil spirit rests upon them. (Orach Chaiim., 4.)

And do not have any regard for God or His word

Thus the tales related to the Torah are simply her outer garments, and woe to the person who regards that outer garb as the Torah itself! For such a person will be deprived of a portion in the world to come.(Lawrence Fine, Chapter on Kabbalistic Texts, From: Back to the Sources: Reading the Classic Jewish Texts (“The First Complete Modern Guide to the Great Books of the Jewish Tradition: What They Are and How to Read Them”), at p. 337 (2006) (quoting Zohar III, 152a).

Jesus disagree with the Pharisees and the oral law quoting Isaiah 29:13 and for that they wanted to kill Him (not exactly in this incident)

Whosoever transgresses the words of the Sages deserves to die (Babylonian Talmud: Tractate Berakoth, Folio 4b, Translated into English with Notes, Glossary and Indices by Maurice Simon, M.A., Under the Editorship of Rabbi Dr I. Epstein B.A., Ph.D., D. Lit. (1961))