The Set Feasts.
“These are the set feasts of Yahweh, even holy convocations, which you shall proclaim in their appointed season.”
The writer now goes on to outline the recurring feasts, ‘the set feasts' other than the Sabbath, which were to occur throughout the year, ‘in their appointed season'. These were almost certainly based on agricultural feasts with which they were already familiar, but with them also being given a new significance. The Patriarchs would certainly have observed such feasts at lambing and at harvest times.
These indicated that not only was the passage of time from Sabbath to Sabbath in His hands, but also the times and seasons. While the earth remained, seedtime and harvest, cold and heat, summer and winter, and day and night would not cease (Genesis 8:22), and they were to recognise the fact and be grateful for it.
The three main feasts, Unleavened Bread, Sevens and Tabernacles, were the times when the men of all Israel would gather together at the Central Sanctuary to worship Yahweh, and to renew the covenant (Exodus 23:14; Deuteronomy 16:16 with 1-17). And every seven years at Tabernacles there would be a reading of the whole covenant (Deuteronomy 31:10-13).