Right in the middle of Parshat Hamoadim, we see the following words: ובקצרכם את קציר ארצכם לא תכלה פאת שדך בקצרך ולקט קצירך לא תלקט לעני ולגר תעזוב אותם, “When you reap the harvest of your field you should not completely remove the corner of your field as you reap and you shall not gather the gleanings of your harvest; for the poor and the convert you shall leave them” (Vayikra 23:22).
Two questions must be asked immediately. First, this Pasuk is talking about the Mitzvot of Peah, Leket, and Shichicha, which require farmers in Eretz Yisrael to leave a portion of the harvest in their fields for poor people to glean. These Mitzvot, however, were mentioned a few Perakim earlier in 19:9-10. Why do we need this repetition? Second, this Pasuk seems to be out of place. How are these Mitzvot connected to the Moadim?
Rashi, Ibn Ezra, and Ramban all deal with this problem. Rashi quotes a Sifra that says that this was placed in the middle of Parshat Hamoadim in order to give the message that anyone who does these Mitzvot properly is considered as if he built the Bait Hamikdash and offered all of its Korbanot. (This connection to Korbanot is presumably based on the fact that the Parshat Hamoadim mentions Korbanot in relation to each Chag.) Ibn Ezra points out that these Mitzvot are placed immediately after Shavuot, which is associated with harvesting in the agricultural cycle. We are therefore reminded that our harvest should be done with these Mitzvot in mind. The Ramban focuses on the use of the word קציר (harvest) in this Pasuk. That Shoresh is used four times in the Pasuk. Earlier in this section, in Pasuk 10, this word is used three times. That Pasuk was talking about bringing the Korban HaOmer on the second day of Pesach. That Korban, of course, begins a process that ends with Shavuot. The Ramban therefore claims that the Torah, upon completion of the discussion of that process, mentions these three Mitzvot, reminding us that when we start the process by harvesting barley for the Korban HaOmer, we must be careful to observe the Mitzvot of Peah, Leket, and Shichicha.
A careful analysis of the Parshat Hamoadim may lead us to an alternate answer to these questions. Clearly, the agricultural cycle is a primary focus of Parshat Hamoadim. Starting with the harvest of barley at Pesach, moving to the harvest of wheat and other crops at Shavuot, and finally to the ingathering of the crops at Succot, there a theme of freedom and opportunity emerges as more and more crops become available to the farmer. The Mitzvot associated with the Chagim in Parshat Hamoadim are therefore designed to temper this freedom and make sure that it is properly focused. In fact, it seems that every time an opportunity arises, there is a preexisting איסור or limitation.
The first example of this is with Pesach. Prior to Pesach, new grain, Chadash, cannot be used (see 23:14). The Korban HaOmer, brought on the second day of Pesach, permits us to consume the new grain. However, when we are presented with that freedom, the איסור of Chametz has already been in effect for a day. Similarly, the freedom and opportunity provided by the harvest of wheat and other crops is associated with Shavuot, which is also the beginning of the זמן בכורים. Perhaps the Torah brings the Mitzvot of Peah, Leket, and Shichicha, at this point to remind us of this preexisting limitation on our freedom to harvest. Continuing along these lines, Succot, associated with the gathering of the crops from the field (see Shemot 23:16), provides limitations on our freedom by requiring us to eat these crops in a Succah and to wave four species of vegetation as a sign of devotion to Hashem.
We can now see how the Mitzvot of Peah Leket, and Shichicha, can assume a central role in the message inherent in the message of the Shalosh Regalim. The Shalosh Regalim teach us that the Torah does not tell us to avoid prosperity and abundance. We are, however, provided with methods of showing an appropriate commitment to Hashem and to other people through these limitations on our freedom.