“When you come to the land… And you shall bring a sheaf of the beginning of your harvest before Hashem!” (Vayikra 23:10-11)
It is a positive commandment that on the second day of Passover, as well as the Additional Offering which is brought on each day of Passover, we should also bring a lamb of the first year as a burnt offering and one sheaf of barley which is called the “waving sheaf”, as it says “When you come to the land… And you shall bring a sheaf of the beginning of your harvest before Hashem. And you shall wave the sheaf before Hashem on the day after the Sabbath!”. When the verse says here the word Sabbath it does not refer to the regular Shabbos. Instead it means the festival as Onkelos says clearly in his translation, “after the good day”, which means to say (directly) after the festival of Passover, which is the second day of Passover, as all of the paragraph is discussing Passover.
The method of bringing the sheaf offering was as follows: They would bring three Seah measurements of barley, and grind it all into fine flour, from which they would extract one measurement of one tenth of an Eiphah sieved with thirteen sieves. They would take this measure and mix it with one Log measurement of oil, and add a handful of frankincense like the other flour offerings. The priest would then wave it in and out, up and down, on the east side of the courtyard of the temple. He would then bring it close to the south western corner of the altar like the other flour offerings, take a fistful of the offering and burn it. The rest would be eaten by the priests like all the other flour offerings.
Amongst the roots of this commandment are that we should reflect on the great kindness that Hashem does with His creations when he renews the food supply for everyone every year. It is therefore fitting that we should bring an offering from the food supply to mention the great kindness and goodness before we start deriving benefit from it. Once we have become fit for blessing by doing the correct actions, our grain will be blessed and Hashem will be happy with us, as with His great goodness He wants only the benefit and blessing of His creations.
We have been commanded to bring this offering on the second day of Passover and not on the first so that we should not mix up the rejoicing on the first day about the great miracles of leaving bondage for freedom with the rejoicing about the fresh produce of the new year.
This commandment applies when the temple was standing to men. Even non-priests have to try to help towards this commandment, as the messengers of the Judges go to the fields and mark bundles of barley for the harvesting which will take place immediately after the festival. Nevertheless, the main obligation is on the priests as the main part of this commandment is the bringing to the courtyard, the waving, bringing near, separating the fistful and burning it, all of which can only be done by the priests.