Easton's Bible Dictionary
There were daily (Leviticus 23), weekly, monthly, and yearly festivals, and great stress was laid on the regular observance of them in every particular (Numbers 28:1-8; Exodus 29:38-42; Leviticus 6:8-23; Exodus 30:7-9; 27:20).
(1.) The septenary festivals were,
(2.) The great feasts were,
(a) The Passover. (b) The feast of Pentecost, or of weeks. (c) The feast of Tabernacles, or of ingathering.
On each of these occasions every male Israelite was commanded "to appear before the Lord" (Deuteronomy 27:7; Nehemiah 8:9-12). The attendance of women was voluntary. (Comp. Luke 2:41; 1 Samuel 1:7; 2:19.) The promise that God would protect their homes (Exodus 34:23, 24) while all the males were absent in Jerusalem at these feasts was always fulfilled. "During the whole period between Moses and Christ we never read of an enemy invading the land at the time of the three festivals. The first instance on record is thirty-three years after they had withdrawn from themselves the divine protection by imbruing their hands in the Saviour's blood, when Cestius, the Roman general, slew fifty of the people of Lydda while all the rest had gone up to the feast of Tabernacles, A.D. 66."
These festivals, besides their religious purpose, had an important bearing on the maintenance among the people of the feeling of a national unity. The times fixed for their observance were arranged so as to interfere as little as possible with the industry of the people. The Passover was kept just before the harvest commenced, Pentecost at the conclusion of the corn harvest and before the vintage, the feast of Tabernacles after all the fruits of the ground had been gathered in.
Of the post-Exilian festivals reference is made to the feast of Dedication (John 10:22). This feast was appointed by Judas Maccabaeus in commemoration of the purification of the temple after it had been polluted by Antiochus Epiphanes. The "feast of Purim" (q.v.), Esther 9:24-32, was also instituted after the Exile. (Cf. John 5:1.)