דברים פרק כה
ב וְהָיָה אִם -ב ִן הַּכ וֹת הָרָ שׁ ָע וְהִפ ִילוֹ הַּשׁ ֹפֵט וְהִכ ָהו לְפָנָיו כ ְדֵי רִ שְׁעָתוֹ ב ְמִסְפ ָר:
ג אַּרְ ב ָעִים יַּכ ֶנ ו לֹא יֹסִיף פ ֶן-יֹסִיף לְהַּכ ֹתוֹ עַּל-הֶ לֵא מַּכ ָה רַּ ב ָה וְנִקְלָה ָ ךיִחָא ָ ךיֶניֵעְל:
Makkos 22a: (Mishnah): One who is lashed receives 39 lashes. "B'Mispar Arba'im" means the number followed by 40; R. Yehudah says, he receives a full 40 lashes; (The Mishnah on 22B teaches that the lashes are evenly divided among three places.) The extra (40th) lash is between his shoulders. We estimate (how many lashes he can survive) only a number divisible by three.
If we estimated that he can survive 40 (really, 39) and after he was lashed some of them we estimate that he cannot bear them, he is exempt (for he was already humiliated).
If we estimated that he can survive 18, and after he was lashed 18 we estimate that he can bear 40, he is exempt.
Even though the verse says the Bais Din administers 40 lashes, nevertheless our tradition is that Bais Din only administers 39 lashes. Why?
Rashi
Written ב ְמִסְפ ָר (and not מִסְפ ָרב ָ by the number) thus to be read “with number forty” but not the whole forty; rather the number which faces (is matched in counting with) and completes to forty, i.e. forty less one (thirty-nine).
Rivan
The two words together (from the end of verse two and beginning of verse three) read ב ְמִסְפ ָר אַּרְ ב ָעִים and not reversed; this implies that the verse refers to a count whose number completes the number forty, which means thirty-nine.
Rambam
The Torah limits to 40 lashes. However, since the counter of the lashes can easily make a mistake of one, limit of lashes is 39 so if made a mistake would not violate the Torah limit of 40.
Malbim
The standard method of the count is to make a lash, count the number and pause. Thus, the Torah is emphasizing that the number of lashes is the pause prior to the number 40 that would have been counted.
Rosh
The method of Torah is to round off upon reaching within one of a “tenth” sum, and not to be concerned about the missing one item (like the matter of 50 days to counting the omer, 70 souls that went to Egypt and these forty lashes.)
Targum Yonasan
Forty times one raises the arm to strike, but only 39 blows are delivered. Raising the arm is as if delivered the fortieth blow.
What is special about 39 and why didn’t the Torah write 39 lashes?
Medrash Tanchuma
Why 40? One that transgresses the Torah which was given in forty days, one should be punished with an increment of forty. Similar to the first sin, in which Adam was punished with 10, Chava with 10, the snake with 10 and the earth with 10. Also, the punishment involving the spies was 40 years in the desert. Plus the formation of a child takes forty days. Then, why only 39 lashes? HaShem does not allow His entire wrath ולא יעיר כל חמתו.
Maharal
Neshamah enters the embryo on the fortieth day. Thus, the set of 39 lashes atones for the 39 days that the body existed without the soul.
Chasam Sofer
It is proper that a person should receive 40 lashes since the Torah that was violated was given in 40 days. However, by the 39th lash a person would submit to the Divine Will, and that would be considered like the additional lash. Or with the 40 lash hanging over a person that leaves a person with a continuing effort to not sin again (something like “V’chatosi negdi samid”).
R’ Bachaye
Lashes are given to a person alleviate the obligation of death (Kores) in order to continue with life. One that is cursed is considered ל"ט. The 39 lashes act to turn the person into טל, water the source of life.
Kli Yakar
One atones with אחד (13), one atones with the 13 Midos HaRachamim, and the Yetzer Tov (good inclination) enters a person at 13 years (3 times 13 =39).
