The Counting of the Omer
6. During thirty-three of the days of the counting of the Omer, Rabbi
Akiva's [24,000] students died (2nd Century CE). Therefore, it is customary
to observe some expressions of mourning during that period; we do not
marry, nor do we have a hair cut (or shave).
There are different customs regarding the determination of which
thirty-three days (of the forty-nine) are observed [in a partial state of
mourning]. According to certain customs, [restrictions] are observed from
the first day of the counting of the Omer, and thus continue until Lag
B'omer (thirty-third day). Even according to this custom, if Rosh Chodesh
Iyar (first day of the Hebrew month called "Iyar") falls on Shabbos, it is
permissible to marry and cut one's hair on the preceding day, for it is
influenced by two sacred qualities ("shtei kedushos"): the holiness of
Shabbos and the holiness of Rosh Chodesh.
These mourning restrictions end on Lag B'omer (and are not applied for the
remaining days) because on Lag B'omer the students ceased
dying. Therefore, certain aspects of celebration are carried out on that
day, and Tachanun is not recited (1). Although some students died on this
day as well, we follow the legal principle which states that: "a portion of
the day is equivalent to the entire day". For this reason, we should not
cut hair or marry until daybreak, and not on the preceding night (2).
When Lag B'omer falls on Sunday, one may have his hair cut on Friday in
honor of Shabbos.
(1) Lag B'omer is also the day on which the great Talmudic Sage, Rabbi
Shimon bar Yochai, passed away. Before he died, he told his students to
commemorate his passing with celebrations.
(2) Observing the restrictions during the night, is counted as if we
observed them the entire day.