"…and you reap its harvest [in Hebrew, "ketsira"], you must bring an omer of your first reaping to the priest. He shall wave it in the motions prescribed for a wave offering to G‑d, so that it will be acceptable for you." (Lev. 23:10-11)

The Torah speaks about "ketsira" [meaning "its harvest"] instead of stating "ketsircha" [meaning "your harvest"] in order to drive home the point that we are reaping a blessing bestowed on the land; we are not reaping the natural fruit of our labor. The fact that the harvest is disproportionably large when compared to the amount of seed planted is a reminder that we are recipients of G‑d's blessing.

Once we bring the "omer" - the measure of barley - as "the first thing harvested" to G‑d, then the Torah describes this harvest as "ketsirchem" [meaning "your harvest"] i.e. it becomes ours. The priest has to wave the omer heavenwards and earthwards to indicate that he is accepting the gift on behalf of G‑d, that it is not like the share of the harvests given to the priests, or like meat portions of the animal sacrifices set aside for the priest. This is also why the Torah stresses "acceptable for you" , i.e. the priest does this to obtain goodwill for you, not for himself. The seven weeks until the festival of Shavuot symbolize the seven days the woman…counts before she immerses herself in a ritual bath…

Should you wonder why the "waving" does not parallel the "waving" of the first fruits (bikurim) of the individual farmer, when the priest places his hand under those of the respective farmer, the Torah says: "on the day following the Shabbat [referring to the very first day of Pesach]". The date of the ceremony is one when the average Jew has not yet attained the degree of holiness to enable him to participate personally. This does not occur until Shavuot, the end of the counting cycle. Since G‑d did not want us to wait until Shavuot before partaking of any of the new harvests, He arranged for the priest to substitute for each individual farmer.

Verse 22 repeats the commandment to show that just as the beginning of the harvest procedure in that year was heralded by performance of a mitzvah, so the storing of the main crops will also be preceded by mitzvot, i.e. provision for the needy.

The Zohar on these verses describes the Jewish people while in Egypt as comparable to a menstruating woman. Engaging in idolatry confers impurity of a similar nature on a person. While a woman who stops menstruating does not automatically become purified, but counts seven days, so the blood of circumcision symbolized the termination of impurity of the Jewish people in Egypt. The seven weeks until the festival of Shavuot symbolize the seven days the woman who has stopped menstruating counts before she immerses herself in a ritual bath and rejoins her husband.

The Torah's emphasis on "on the day following the Shabbat", that the omer is being offered on the day immediately following cessation of the active ingredients of impurity - but before the days of purification have been completed, explains why the omer can be offered only by the priest. The fact that it consists of barley, essentially animal fodder, as opposed to wheat, food fit for man, underscores that collectively the Jewish people did not attain the status of human beings in the full sense of the word until Shavuot, until they had completed the predication cycle.

This also explains why the Torah here refers to the first day of Pesach as "Shabbat", instead of the more usual "Shabbaton", such as regarding the festivals of Rosh Hashanah, Yom Kippur, and Sukkot. The "Shabbat" element, then, is the cessation of impurity due to the blood of circumcision and that of the Pascal lamb which was being offered prior to the first night of Pesach.