SHAVUʿOT , or Pentecost, is the Jewish festival that falls on the sixth day of the month of Sivan (and also on the seventh day, outside Israel). In the Pentateuch (Ex. 34:22, Dt. 16:10) the festival is called Shavuʿot ("weeks") because it falls after seven weeks (forty-nine days) have been counted from the "morrow of the Sabbath" (Lv. 23:15) of Passover. In the Talmudic literature a debate is recorded between the Sadducees and the Pharisees: the former understood the word Sabbath in the verse to mean literally the Sabbath of Passover (so that, for them, Shavuʿot always fell on Sunday), while the latter, whose view is accepted, understood "the Sabbath" to be the first day of Passover. It is difficult to know what doctrinal issues really lie behind these two opinions, since, if the report is accurate, it is unlikely that the debate was purely exegetical.
In the Pentateuch the festival appears to have been a purely agricultural one. The rabbinic name for the festival, ʿAtseret ("assembly"), the term used in Numbers 29:35 for the additional festival of Sukkot, suggests that originally the festival was no more than an adjunct to Passover. But beginning no later than the second century ce a vast transformation of the festival took place. The arrival at Mount Sinai of the people coming from slavery in Egypt (Ex. 19:1) occurred in the third month from the Exodus (the month of Sivan, as it came to be called). Through examination of the texts, a view developed that the theophany at Sinai had taken place on the sixth of Sivan, and Shavuʿot was then celebrated as the anniversary of the giving of the Torah. (Although the passage speaks only of the Decalogue being given at Sinai, later Jewish tradition held that the whole of the Torah was given to Moses at that time.)
The liturgy of the day contains references to the Torah and the 613 commandments (the rabbinic figure for the sum total of positive precepts and negative injunctions of the law). A feature found only on this festival is the recital of an Aramaic hymn on the first day in praise of the Torah. It is generally held that these hymns are vestiges of introductions in Aramaic to the Targum, the Aramaic translations of the texts that, in ancient times, were always read in the synagogue. The Pentateuchal reading is from the Sinai narrative (Ex. 19–20), and the Prophetic reading from Ezekiel 1, the vision of the heavenly chariot. The link between the two is that of revelation, to the people as whole and to the individual prophet. The Book of Ruth as well is read in the synagogue. Ruth, the prototype of the righteous proselyte, took upon herself the observance of God's laws, as did the Israelites at Sinai.
There are no special Shavuʿot rituals, in view of the late origin of the festival in the form in which it is now celebrated. However, there are a number of customs, such as decorating the synagogue with plants and flowers (because beautiful plants are said to have flowered on the barren mountain when the Torah was given) and eating dairy dishes at the festive meal (because, like milk, the Torah nourishes young and old). The sixteenth-century mystics of Safad introduced the all-night vigil on Shavuʿot night, a practice that has been widely adopted by all Jews. During this night an anthology of readings from all the classical sources of Judaism is studied.
The little book by Chaim Pearl, A Guide to Shavuoth (London, 1959), is an adequate statement of the laws and customs of the festival.
Louis Jacobs (1987)
"Shavuʿot." Encyclopedia of Religion. . Encyclopedia.com. (August 15, 2018). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/shavuot
"Shavuʿot." Encyclopedia of Religion. . Retrieved August 15, 2018 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/shavuot