Rabbi Elazar said: It is written: “They did not say in their heart: Let us now fear the Lord our God, [who gives rain, the early rain and the late rain at its appointed time; the set weeks of the harvest, He will maintain for us]” (Jeremiah 5:24). He has given you everything; do you not need Him now? “The set weeks of the harvest, He will maintain for us” – He will protect us from harmful winds and harmful dew.6Although the rain has already fallen, God’s protection is still needed, as harmful rains and dew can ruin the crops.
When? It is during the seven weeks between Passover and Shavuot.7The midrash is suggesting that the need for God’s protection is the reason for the mitzva of the omer offering, which is brought on the second day of Passover, as well as the mitzva to count the forty-nine days from the day of the omer offering (Etz Yosef). Rabbi Ḥiyya taught: “Seven weeks, they shall be complete” (Leviticus 23:15). When are they complete?
When Israel performs the will of the Omnipresent. Rabbi Yehoshua said: ‘I am your Watchman; will you not give Me payment for my watching?’8This is stated from the perspective of God, and serves as an explanation for the reason the omer offering is brought. Rabbi Berekhya said: ‘I am your Cook; will you not allow Me to taste your cooked items, to know what they need, whether dew or rain?’ “You release rain abundantly, God” (Psalm 68:10); David said before the Holy One blessed be He: ‘Master of the universe, if it needs rain, [give it] “abundantly [nedavot]”;9The word nedavot can also be translated as “free gifts,” such that the meaning here could be: ‘Give it as a free gift’ (see Matnot Kehuna). if it needs dew, release it, God.’
Rabbi Berekhya said: The Holy One blessed be He said to Moses: ‘Go and say to Israel: When I would give you manna, I would give an omer to each and every one of you. That is what is written: “An omer per person” (Exodus 16:16). Now that you are giving Me the omer, I have only one omer from all of you. Moreover, it is not of wheat, but of barley.’
Therefore, Moses cautions Israel and says to them: “You shall bring a sheaf [omer].”10Given God’s great kindness, it would be particularly ungrateful if they were not careful to bring the omer offering.