Chapter 120:1
The Counting of the Omer
1. On the second night of Pesach, one begins "counting the Omer" (1). One
must count while standing (2). The mitzvah is to count immediately at the
beginning of the night (3), as soon as [three medium-size stars] become
visible (4). If one did not count at the beginning of the night, the time
for counting extends throughout the entire night.
On Shabbos and festivals nights, the counting takes place in synagogue
after the recitation of Kiddush (after Maariv, the evening service), in
order to give precedence to the [proclamation] of the sanctity of the
day. At the conclusion of Shabbos or a holiday, we count before the
recitation of Havdalah in order to delay the departure of the [holy]
day. Should the final day of Pesach fall on Saturday night, and hence
Kiddush and Havdoloh are recited over the same cup of wine, we count
beforehand in order to delay the recitation of Havdalah (which signifies
the end of Shabbos).
FOOTNOTES:
(1) When the Beit Hamikdash (Temple) was standing in Jerusalem, there was a
mitzvah to begin the grain harvest season by harvesting a certain amount of
barley on the second night of Pesach, and bringing the amount of one "omer"
(approx. 2 quarts) as a meal offering ("Korban Mincha") in the Beit
Hamikdash the next day (See Leviticus 23:9-14).
There is another mitzvah for each male to verbally count seven weeks
(counting each of the 49 days and seven weeks), beginning from the day the
"omer" offering is brought (hence the name "Counting of the Omer"), that
is, the second day of Pesach, and ending on the day before the festival of
Shavuos (lit: "weeks" - because it is the culmination of 7 weeks of
counting) (See Leviticus 23:15-22).
Now that there is no longer a Beit Hamikdash, and hence, no longer an
"Omer" offering brought on the second day of Pesach, there are many
authorities who rule that the mitzvah of counting is only a rabbinically
ordained obligation.
As with most mitzvos that have to be performed at a specific time, women
are exempt from the mitzvah of counting; however, women in many communities
accepted this mitzvah upon themselves, as they did the mitzvah of lulav and
shofar; therefore, if a woman desires to count, she may do so, however,
some authorities question whether a blessing may be recited (See Mishna
Berura 489:3).
(2) But if one counted while sitting, one has fulfilled one's obligation
and need not count again.
(3) The verse says to count "seven COMPLETE weeks", therefore we try to
count as soon as the new day begins (that is, at the beginning of the
night), so that each counting is for a "complete" day.
(4) After the Maariv Shmone Esrei, before Aleynu.