In this chapter, the LORD restates the regulations concerning the Sabbath, appointed ceremonial feasts and Day of Atonement (commonly known as Yom Kippur).
This chapter is largely a recapitulation of prior laws we have read. Some of these have expanded detail, but I think the main purpose of this chapter is to state the laws governing religious festivals in a single place in the Levitical law, because these festivals directly relate to the work of the priests. It is confusing to keep track of the many places these festivals are referenced because these references span across much of the Pentateuch and beyond. To facilitate study, I will include the primary references for these festivals here. Probably the hardest part about gathering all the references together is that the bible uses many terms to refer to the same feasts.
For instance, the "Festival of the harvest" is the same thing as the "feast of weeks" is the same as the "day of the first fruits" is the same as "Pentecost" is the same thing as "Shavuot". The last is the modern name, the first 4 are all used as references in the bible (crossing both OT and NT). It's as if the American Independence Day were also called "Fourth of July", "Freedom Day", "Founders' Day", "The Celebration of Triumph", etc. Of course, it actually is called both Fourth of July and Independence Day, but we see a much greater multiplication of terms for the OT festivals. This makes it difficult to search for a specific festival by keyword (both English and Hebrew), and the variation amongst translations makes it even more challenging. I wanted to include all of the references to these festivals, but I simply can't guarantee I find all of them given how many terms are used for these ceremonies. I will do this later, give a full summary of all major holidays and references, but only towards the end of the Pentateuch when I can include everything.
First is the Sabbath (v. 3), which is referenced in many places (more than nearly any other holiday). The primary reference for the Sabbath is Ex 16, with smaller references or extensions in Ex 20:8-11, an implied reference in Ex 23:10 et al., Ex 31:12 et al. (Do you remember the Sabbath? If not, I will restate the entire law of the Sabbath for you in case you forgot), Ex 35:1-3 (No, really, obey the Sabbath. Also, don't kindle a fire on the Sabbath.), Lev 19:3 and Lev 19:30. There is an implied reference in Gen 2:2. After all that, the author decided he wasn't done restating the law of the Sabbath, and it seemed appropriate to tell us about the Sabbath again here in Lev 23. I would put more sarcastic commentary here, but in later books of the bible we will learn that the people of Israel frequently did not observe the Sabbath. So that's ironic and more than a little sad.
Second is the Passover (v. 4-8), which is probably about equivalent with the Day of Atonement as the second-most referenced Hebrew holiday. The Passover is very closely related to the Feast of Unleavened Bread, so I will treat them as if they were the same thing. The primary reference for the Passover is Ex 12 with the Feast of Unleavened Bread in Ex 13 with minor references in Ex 23:15, Ex 34:18, and a possibly implied reference in Gen 22.
After the Passover is a somewhat confusing passage (v. 9 to 14) that talks about a wave offering of "the sheaf of the first fruits of your harvest" which is to be done "after the Sabbath". Since it's talking about an offering of first fruits, I naturally presumed that it refers to the Feast of Weeks, which is about the offering of the first fruits. However, v. 15 makes it clear that the Feast of Weeks must occur 50 days after the wave offering of the sheaf, so 9-14 must be referring to something that occurs during or after the Passover ceremony. We are not told what Sabbath is meant, and I've read modern commentaries are divided on the subject. Clearly it must have been near or during the Passover, however.
I believe this sacrifice is intended as a token offering of thanks to the LORD before they eat anything themselves, similar to the modern Christian concept of "saying grace" before eating a meal. However, it's unclear to me why there is this and then a separate celebration of the first fruits 50 days later. Maybe the Feast of Weeks is a celebration of the beginning of the harvest while the Feast of Ingathering is a celebration of the end? In which case, the Passover occurs at the very beginning of the earliest part of the harvest, when the very first crops begin producing fruit (well, grain). I'm not sure.
Third is the Festival of the Harvest of first fruits (v. 15-21). This is established in Ex 23:16 and again in Ex 34:22, where it is called the Feast of Weeks. This festival is mentioned a few times in the biblical text, and becomes a substantial story element in Acts 2, where it is called the Pentacost (i.e. 50th day, roughly beginning with the Passover). However, the Feast of Weeks is rarely mentioned in the OT itself and is essentially ignored after Deuteronomy. So of the three mandatory gatherings of the whole nation, this is probably the least important. One strange thing we learn in this chapter is that for the Feast of Weeks, the loaves of bread are to be leavened (v. 17), contrary to the Passover rituals. The earlier references to the Feast of Weeks only mentioned that "they must be observed"; now we are told that this festival must also have a variety of sacrificial offerings (v. 18-19). By now we should be very used to sacrificial offerings in Leviticus, but since the proper form for these sacrifices had not yet been defined in Exodus, we are only told now about the sacrifices that go along with the feasts. I.e. Leviticus 1-5 defined the regulations for these sacrifices, so only after that can these sacrifices be properly understood.
Fourth is the Festival of Trumpets (commonly known as Rosh Hashanah, v. 24-25). This is the first mention of the Feast of Trumpets. Also, note that feast of trumpets is a mere 9 days before Yom Kippur, so you have a festival briefly before a day of fasting. Then five days after Yom Kippur is the Festival of Booths (sometimes known as Sukkot), which is the same thing as the Festival of Ingathering from Ex 23 and Ex 34. This is a very compressed schedule to have three major festivals within 15 days, and it coincides with the customary celebrations at the end of the harvest (a traditional time of plenty and rejoicing in many agricultural societies). I think it's worthwhile for me to remind my readers of the tremendous shift we are witnessing as Israeli society is re-engineered from a predominantly pastoral culture to a predominantly agrarian culture. Just two books ago, in Genesis, we read about Abraham wandering throughout the promised land and traveling down to Egypt to survive through famines. Now in this book we have multiple feasts scheduled throughout the year to match with transitions in the agricultural calendar, from the first fruits to ingathering. This is a very dramatic shift, and yet as we will observe, a pastoral tradition will remain in Israelite society for most of the rest of the OT.
Anyway, we are told very little about Rosh Hashanah here; simply that there is a blowing of trumpets and then a holy convocation.
Fifth is Yom Kippur, the Day of Atonement (v. 26-32). This ritual is established in substantial detail in Lev 16 and is only briefly mentioned here, with a much greater emphasis on the demand for a Sabbath-like cessation of labor than on the formal priestly offerings laid out in Lev 16.
Sixth is the Feast of Booths (v. 33-36, 39-43), or the Festival of Ingathering, (now known as Sukkot, which means booths). Like the Festival of the Harvest, this is first (briefly) established in Ex 23:16 and 34:22. This is one of the less important festivals. Although this festival was mentioned before, only here are we told that the people are expected to live in booths. Before it was called the Festival of Ingathering, to highlight the agricultural connection, but now it's called the Feast of Booths to emphasize its connection to the wanderings in the desert, the nomadic past when Israel did not live in permanent settlements.
This obvious implication is that while Israel was previously nomadic, in the future when they celebrate this feast they will be living in permanent houses, which also explains why there are regulations for moldy houses. This transition from nomadic wandering to permanent settlements correlates strongly with the transition from shepherding to farming. Naturally, raising livestock requires grazing land, which is usually migratory as the flock consumes grass from one place and moves on to the next. On the other hand, farming requires nearly continuous maintenance of a fixed patch of land for virtually the entire year, creating both a need and an opportunity to build fixed structures.
This festival, then, is backward-looking, even though it's being instituted in a time when Israel is still wandering in the desert. So that's interesting. Of course, all of these wanderings are with the firm expectation of moving into the promised land, which will be settled.
On a minor note, a day runs from evening to evening, not midnight to midnight (as in the current time system). We see this in v. 32. This is how Hebrews count time throughout the OT and while it's not very important, it's a little important.
This chapter highlights the fragmented nature of the OT because the feasts that it is drawing together come from so many places. Even though this chapter omits the New Moon Sabbaths (established later), it is still probably the most complete listing of religious feasts in the entire OT.