Notes (NET Translation)
17 The LORD spoke to Moses:
18 “Speak to the Israelites and tell them, ‘When you enter the land to which I am bringing you 19 and you eat some of the food of the land, you must offer up a raised offering to the LORD.
In Mishnah Ḥallah 1:1, the rabbis applied this law to five kinds of grain indigenous to the land of Israel: wheat, barley, spelt, oats, and rye, but not to rice, millet, or pulse.1
20 You must offer up a cake of the first of your finely ground flour as a raised offering; as you offer the raised offering of the threshing floor, so you must offer it up.
The offering consists of the earliest and choicest of the crops. But it is an offering from the threshing floor, not standing grain.
Normally, the substances for cultic offerings were set aside or dedicated in the first instance before being converted into food. The present provision is an exception, because it applies to the dough, not to the grain used to make dough, or even to the flour.2
The amount of the reʾshit is never specified. It would seem to refer to the first loaf. The rabbis, however, stipulate that ḥallah is minimally one omer, enough to fill a vessel 10 x 10 x 3.25 inches, of which 1/24 goes to the priest in the case of a private householder and 1/48 in the case of a bakery.3
21 You must give to the LORD some of the first of your finely ground flour as a raised offering in your future generations.
The firstfruits were given to the priests (Num 18:11-16; Ezek 44:30).
Ashley, Timothy R. The Book of Numbers. The New International Commentary on the Old Testament. Grand Rapids, MI: Eerdmans, 1993.
Brown, Raymond E., Joseph A. Fitzmyer, and Roland E. Murphy, eds. The New Jerome Biblical Commentary. Englewood Cliffs, NJ: Prentice Hall, 1990.
Cole, R. Dennis. Numbers. Kindle Edition. The New American Commentary. Nashville, Tennessee: Broadman & Holman Publishers, 2000.
Friedman, Richard Elliott. Commentary on the Torah. First Edition. San Francisco, Calif.: HarperOne, 2001.
Levine, Baruch A. Numbers 1-20. The Anchor Yale Bible. New Haven: Yale University Press, 1993.
Mays, James L., ed. The HarperCollins Bible Commentary. Revised Edition. San Francisco: HarperSanFrancisco, 2000.
Milgrom, Jacob. Numbers. The JPS Torah Commentary. Philadelphia: Jewish Publication Society, 1989.
Wenham, Gordon J. Numbers. Kindle Edition. Tyndale Old Testament Commentaries. IVP Academic, 2015.