GG. The three pilgrimage feasts
The earliest system of festivals is recorded in the Covenant Code (Exod. 23:14-17 / 34:18-24). The Covenant Code description is very simple, and no exact dates are given. Exod. 23:14 stipulates that all Israelite males must appear before the Lord and keep a feast “three times a year" (the pilgrimage; חג) is later called ‘aliyah, i.e., “ascent.”
These three feasts are the so-called “Pilgrim Feasts” (שלש רגלים); i.e., Feast of Unleavened Bread (חג המצות), Feast of the Harvest (חג הקציר; aka "feast of first fruits"), and Feast of Ingathering (חג האסף). Although different in many details, Unleavened bread, Harvest, and Ingathering share in common the pilgrimage to Jerusalem. In addition to their connection to the agricultural cycle (as indicated by the earliest names for the festivals), they also gain a theological-historical explanation. Some scholars claim that the two different origins of each festival are independent, with the agricultural source antedating the theological-historical one.
1. The Feast of Unleavened Bread (חג המצות; aka Mazzot; later becomes connected to Passover/Pesach) is to be celebrated “for seven days at the appointed time in the month of Abib” (23:15). In this earliest system (i.e. Covenant Code), it seems that פסח and מצות were considered to be two separate festivals, with פסח celebrated the night before the beginning of מצות.
2. The Feast of the Harvest (חג הקציר ; also called Shavuot, Weeks, Pentecost) was to apparently be celebrated when the “first fruits of your labor” were collected (23:16; see also Judg. 9:27, which may describe a similar festival observed by the Canaanites). Exod. 34:22 calls the Feast of the Harvest “Shavu‘ot,” because it is to be observed seven weeks after the harvest begins.
3. The Feast of Ingathering (חג האסף; also known as Sukkot, Booths, Tabernacles) occurs at the end of the year, “when you gather in from the field the fruit of your labor” (23:16). Thus, we have two distinct harvest festivals, one at the first round of harvest (Shavuot/Feast of Harvest) and one at the year’s end (Feast of Ingathering). The older "Ingathering" or "Fruit-Harvest" festival became a commemoration of the 40 years that the Hebrew wandered in the desert, living in temporary shelters like tents or "booths" (Lev 23:33-36, 39-43; Deut 16:13-15).