The Power Of Shaking Hands


Tzvi wished to buy an antique book from Boruch, a fellow dealer in
Judaica. They agreed on a price and shook hands on the deal. The next day,
when Tzvi came to deliver the payment, Boruch declared that he had changed
his mind and did not wish to sell. Tzvi objected to this retraction, arguing
that shaking hands constitutes irreversible conclusion of a deal in the
Judaica trade. Is this argument valid?


The Torah prescribes different kinyonim (methods
of acquisition) for different items. Movable items are acquired by means of
hagbo’oh (lifting) or meshicha (pulling along the ground). In
the wine trade it was customary for retailers to buy large quantities of
wine and leave their purchases in the wholesaler’s cellars. They would take
each wine barrel to their shop as it was needed. When making their initial
purchase, they would mark each barrel with their own personal symbol (situmta).
In Tractate Bovo Metzia (74a), our Sages state that if the custom is
to acquire barrels of wine by making this mark, such marking is binding. The
purchaser becomes obligated to pay for the wine; the seller is unable to
change his mind on the deal, just as if the purchaser had made meshicha
on each barrel (Rashi). The Rosh (5:72) quotes Rabbenu
, who explains that when merchants conclude a deal by shaking
hands, the deal is also binding. As in the case of marking wine barrels, in
this trade the custom is to conclude a deal with a handshake. The
established custom creates a halachically binding transaction. Furthermore,
if the custom dictates that such acts only create an obligation to sell but
not an actual sale, then the item is not considered sold. However, since an
obligation to sell has been agreed to, whoever backs out of the deal
receives a mi shepora curse (Hashem will curse one who does
not keep his word). All the above rulings are to be found in the Shulchan
(Choshen Mishpot 201:1 and 2).

We can therefore conclude that if Tzvi can produce
evidence that a handshake signifies completion of a sale in the Judaica
trade, he can force Boruch to proceed with the deal. However, even if such
evidence is not forthcoming, it is possible that Boruch has entered into an
obligation to sell, albeit that the item is not yet sold. Maharil
(Responsa, 1:126) questions whether acts of acquisition which are
only valid by virtue of custom can create an obligation. The Emek
(1:24) brings proof that the custom can indeed create an
obligation. He cites Tosafos (Bovo Metzia 66a), who discuss
the validity of the financial penalties which the fathers of the bride and
groom accept upon themselves for non-fulfilment of their obligations.
come to the conclusion that such an undertaking is valid,
comparing it to the marking of barrels by wine retailers. The basis of his
argument is that even though this seems to be no more than a promise, since
it is the accepted custom for the parties to obligate themselves in this
way, it is binding. Thus, argues the Emek HaMishpot, we find that not
only does custom dictate that certain actions constitute an act of
acquisition, it also determines that other actions create an obligation.

We would therefore conclude that Boruch should sell the book to Tzvi.
Even if Tzvi is unable to produce evidence that shaking hands constitutes a
sale, it may create an obligation to sell. However, if Boruch backs out of
his undertaking to sell, he does not receive a mi shepora curse (see
Achiezer 3:40:4). In any event, such retraction would classify him as
an unreliable person (mechusar amonoh).

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