A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
lev 23:2OF SUNDRY FEASTS. (Lev 23:1-4)
Speak unto the children of Israel, . . . concerning the feasts of the Lord--literally, "the times of assembling, or solemnities" (Isa 33:20); and this is a preferable rendering, applicable to all sacred seasons mentioned in this chapter, even the day of atonement, which was observed as a fast. They were appointed by the direct authority of God and announced by a public proclamation, which is called "the joyful sound" (Psa 89:15). Those "holy convocations" were evidences of divine wisdom, and eminently subservient to the maintenance and diffusion of religious knowledge and piety.
lev 23:3Six days shall work be done: but the seventh day is the sabbath of rest--(See on Exo 20:8). The Sabbath has the precedence given to it, and it was to be "a holy convocation," observed by families "in their dwellings"; where practicable, by the people repairing to the door of the tabernacle; at later periods, by meeting in the schools of the prophets, and in synagogues.
lev 23:4These are the feasts of the Lord, which ye shall proclaim in their seasons--Their observance took place in the parts of the year corresponding to our March, May, and September. Divine wisdom was manifested in fixing them at those periods; in winter, when the days were short and the roads broken up, a long journey was impracticable; while in summer the harvest and vintage gave busy employment in the fields. Besides, another reason for the choice of those seasons probably was to counteract the influence of Egyptian associations and habits. And God appointed more sacred festivals for the Israelites in the month of September than the people of Egypt had in honor of their idols. These institutions, however, were for the most part prospective, the observance being not binding on the Israelites during their wanderings in the wilderness, while the regular celebration was not to commence till their settlement in Canaan.
lev 23:5THE PASSOVER. (Lev 23:5-8)
the Lord's passover--(See Exo 12:2, Exo 12:14, Exo 12:18). The institution of the passover was intended to be a perpetual memorial of the circumstances attending the redemption of the Israelites, while it had a typical reference to a greater redemption to be effected for God's spiritual people. On the first and last days of this feast, the people were forbidden to work [Lev 23:7-8]; but while on the Sabbath they were not to do any work, on feast days they were permitted to dress meat--and hence the prohibition is restricted to "no servile work." At the same time, those two days were devoted to "holy convocation"--special seasons of social devotion. In addition to the ordinary sacrifices of every day, there were to be "offerings by fire" on the altar (see Num 28:19), while unleavened bread was to be eaten in families all the seven days (see Co1 5:8).
lev 23:10THE SHEAF OF FIRST FRUITS. (Lev 23:9-14)
ye shall bring a sheaf of the first-fruits of your harvest unto the priest--A sheaf, literally, an omer, of the first-fruits of the barley harvest. The barley being sooner ripe than the other grains, the reaping of it formed the commencement of the general harvest season. The offering described in this passage was made on the sixteenth of the first month, the day following the first Passover Sabbath, which was on the fifteenth (corresponding to the beginning of our April); but it was reaped after sunset on the previous evening by persons deputed to go with sickles and obtain samples from different fields. These, being laid together in a sheaf or loose bundle, were brought to the court of the temple, where the grain was winnowed, parched, and bruised in a mortar. Then, after some incense had been sprinkled on it, the priest waved the sheaf aloft before the Lord towards the four different points of the compass, took a part of it and threw it into the fire of the altar--all the rest being reserved to himself. It was a proper and beautiful act, expressive of dependence on the God of nature and providence--common among all people, but more especially becoming the Israelites, who owed their land itself as well as all it produced to the divine bounty. The offering of the wave-sheaf sanctified the whole harvest (Rom 11:16). At the same time, this feast had a typical character, and pre-intimated the resurrection of Christ (Co1 15:20), who rose from the dead on the very day the first-fruits were offered.
lev 23:15FEAST OF PENTECOST. (Lev 23:15-22)
ye shall count unto you from the morrow after the sabbath--that is, after the first day of the passover week, which was observed as a Sabbath.
lev 23:16number fifty days--The forty-ninth day after the presentation of the first-fruits, or the fiftieth, including it, was the feast of Pentecost. (See also Exo 23:16; Deu 16:9).
lev 23:17Ye shall bring out of your habitations two wave loaves of two tenth deals, &c.--These loaves were made of "fine" or wheaten flour, the quantity contained in them being somewhat more than ten pounds in weight. As the wave-sheaf gave the signal for the commencement, the two loaves solemnized the termination of the harvest season. They were the first-fruits of that season, being offered unto the Lord by the priest in name of the whole nation. (See Exo 34:22). The loaves used at the Passover were unleavened; those presented at Pentecost were leavened--a difference which is thus accounted for, that the one was a memorial of the bread hastily prepared at their departure, while the other was a tribute of gratitude to God for their daily food, which was leavened.
lev 23:21ye shall proclaim on the selfsame day, that it may be an holy convocation unto you: ye shall do no servile work therein--Though it extended over a week, the first day only was held as a Sabbath, both for the national offering of first-fruits and a memorial of the giving of the law.
lev 23:22thou shalt not make clean riddance of the corners of thy field when thou reapest, &c.--(See on Lev 19:9). The repetition of this law here probably arose from the priests reminding the people, at the presentation of the first-fruits, to unite piety to God with charity to the poor.
lev 23:24FEAST OF TRUMPETS. (Lev 23:23-25)
In the seventh month, in the first day of the month, shall ye have a sabbath--That was the first day of the ancient civil year.
a memorial of blowing of trumpets--Jewish writers say that the trumpets were sounded thirty successive times, and the reason for the institution was for the double purpose of announcing the commencement of the new year, which was (Lev 23:25) to be religiously observed (see Num 29:3), and of preparing the people for the approaching solemn feast.
lev 23:27there shall be a day of atonement . . . and ye shall afflict your souls--an unusual festival, at which the sins of the whole year were expiated. (See Lev 16:29-34). It is here only stated that the severest penalty was incurred by the violation of this day.
lev 23:34the feast of tabernacles, for seven days unto the Lord--This festival, which was instituted in grateful commemoration of the Israelites having securely dwelt in booths or tabernacles in the wilderness, was the third of the three great annual festivals, and, like the other two, it lasted a week. It began on the fifteenth day of the month, corresponding to the end of our September and beginning of October, which was observed as a Sabbath; and it could be celebrated only at the place of the sanctuary, offerings being made on the altar every day of its continuance. The Jews were commanded during the whole period of the festival to dwell in booths, which were erected on the flat roofs of houses, in the streets or fields; and the trees made use of are by some stated to be the citron, the palm, the myrtle, and the willow, while others maintain the people were allowed to take any trees they could obtain that were distinguished for verdure and fragrance. While the solid branches were reserved for the construction of the booths, the lighter branches were carried by men, who marched in triumphal procession, singing psalms and crying "Hosanna!" which signifies, "Save, we beseech thee!" (Psa 118:15, Psa 118:25-26). It was a season of great rejoicing. But the ceremony of drawing water from the pool, which was done on the last day, seems to have been the introduction of a later period (Joh 7:37). That last day was the eighth, and, on account of the scene at Siloam, was called "the great day of the feast." The feast of ingathering, when the vintage was over, was celebrated also on that day [Exo 23:16; Exo 34:22], and, as the conclusion of one of the great festivals, it was kept as a sabbath.