The Torah (Vayikra 19:27) prohibited the removal of a mans sideburns, and the barber who violates this prohibition is punished with lashes if he did so after being warned of the consequences of his action by witnesses. What about the fellow getting the haircut who receives a similar warning?

When Rabbi Chisda heard one of his disciples quote a ruling that both of them are liable for lashes he expressed his amazement in a most unusual fashion. "Shall one who eats dates in a sieve receive lashes?" he asked. His challenge was based on the principle that lashes are administered only for an active violation of a Torah prohibition and this should not apply to the one receiving the haircut because he is guilty of a passive violation.

Rabbi Ashi refuted this challenge by explaining the case in question as one in which the fellow receiving the haircut assists the barber by positioning his head, so that he too is guilty of an active violation. But a mystery remains as to what Rabbi Chisda intended with his comparison of the passive fellow in the barber chair to someone eating dates in a sieve!

Ritvas explanation is that he was referring to a case in which someone ate from a sieve dates that had sinfully been picked from a tree by another Jew on a holiday. Just as he would not be liable for lashes because it was not he who did the picking in violation of Torah law, so too should the fellow getting the haircut be free of lashes since he was not involved in active violation.

Rabbi Yacov Ettinger, in his "Aruch Laner" commentary finds this explanation too remote and offers an alternative one which gives meaning to the sieve mentioned in Rabbi Chisdas challenge. The mishna in Mesechta Keilim (15:3) mentions a sieve which was used by women hairdressers to catch the hair they cut from their clients. It may therefore be assumed that it was common practice to place the man receiving a haircut in such a sieve-like net to prevent the hair from dirtying the area. What did the fellow do as he sat idle while his hair was being cut? He ate dates! But why should he receive lashes, asked Rabbi Chisda, if the only thing he did actively was to eat these dates while seated in the sieve?

The big problem with both of these ingenious approaches is that they are hardly applicable to Rabbi Chisdas use of the same phrase in Mesechta Sanhedrin (89b). We must conclude that once he coined the phrase here Rabbi Chisda decided to use it elsewhere even if only remotely applicable.

Maccot 20b

In order to communicate a lesson to the sinner condemned to 39 lashes for violating a prohibition of the Torah, passages from Torah and Tehillim are read to him by one of the judges administering the penalty. Four passages are mentioned in the Mishna Devarim 28:58, Devarim 28:59, Devarim 29:8 and Tehillim 78:38.

The common denominator of these passages is the theme of Divine justice applied to those who fail to honor the covenant between Hashem and His people. The last three aforementioned passages also have something else in common they each contain exactly thirteen words.

This number is not coincidental. The 39 lashes, after all, are divided into three equal sections. One set of 13 is applied to the chest and two sets of thirteen each to the back at the shoulders. Each word of these three passages thus corresponds to one of the blows.

The first passage, however, contains 21 words and does not seem to fit in with this pattern. Maharsha therefore suggests that this passage was read as an introduction to the lashes but not while they were administered, in accordance with the word count of the succeeding passages.

There is a mention in Shulchan Aruch Orach Chaim 607:6 of a custom for Jews to administer to one another very token lashes on Erev Yom Kippur in order to stimulate thoughts of repentance. Since these are not lashes in a real sense because no court today has the authority to issue such a sentence, and the one receiving the lashes received no formal warning, the only passage said by the lasher three times is the last one which stresses Divine mercy even in the administration of justice.

Maccot 22b