I learned that starting from the second night of Passover, we count 49 days until the holiday of Shavuot, and this counting is known as Sefirat HaOmer, the Counting of the Omer. I’m wondering, why do we count the Omer specifically at night?


Let’s first understand the origin of the term “Omer.” The Omer was actually an offering brought in the Holy Temple on the second day of Passover, containing an omer measure of barley from that year’s new crop. The barley would be harvested the night before and offered up on the altar that day. It was forbidden to eat from that year’s new crops until the Omer was offered on the altar.

This only strengthens your question. If the Omer was brought during the day, why does the count begin at night?

The answer is that the Torah specifies that the counting should be “complete”: “[And] you shall count for yourselves, from the morrow of the rest day from the day you bring the Omer as a wave offering seven weeks; they shall be complete.”1

The only way to have a “complete count” is if the counting begins during the preceding night, since the day begins with the night in Jewish law.2 (In the creation story, the Torah tells us: “ . . . And it was evening and it was morning, one day.”3)

Sefirat HaOmer is actually somewhat of an anomaly. Unlike all other areas of the Torah, when it comes to Temple offerings, a “day” is considered the daytime and its following night. Since the Torah correlates Sefirat HaOmer with the Omer offering, it would have made sense to begin counting in the daytime. However, in order to have a “complete count,” we start counting during the preceding night.

And since the Torah intends for us to start counting the Omer at night, it stands to reason that we should continue to perform this mitzvah at night, so that we have a “complete count” for all 49 days of the Omer.4

On a deeper level, the Lubavitcher Rebbe explains that the concept of Sefirat HaOmer is a 49-day process of refining the darkness of the world; thus, it is appropriate for the counting to be done at night. At the same time, the counting correlates with the Omer offering, for which the day precedes the night. This symbolizes the light and G‑dliness that pervades the world through the mitzvah of Sefirat HaOmer.5

For more on the Counting of the Omer, see Sefirat HaOmer.