וְהָלְכ֤וּ בָנָיו֙ וְעָשׂ֣וּ מִשְׁתֶּ֔ה בֵּ֖ית אִ֣ישׁ יוֹמ֑וֹ וְשָׁלְח֗וּ וְקָרְאוּ֙ לִשְׁלֹ֣שֶׁת אחיתיהם [אַחְיֽוֹתֵיהֶ֔ם] לֶאֱכֹ֥ל וְלִשְׁתּ֖וֹת עִמָּהֶֽם׃
И сыновья его ходили и устраивали праздники в доме каждого в день свой; и они посылали и приглашали своих трех сестер есть и пить с ними.
Sforno
עצרת היא. The concept of עצירה is something apart from the concept of שביתות. The latter pertains to abstaining from ordinary secular activities, whereas the former entails spending a certain amount of time performing holy tasks, studying Torah, engaging in communal prayer, etc. The expression נעצר occurs in this context in Samuel I 21,8 ושם איש מעבדי שאול ביום ההוא נעצר לפני ה', “and there was a man, one of Saul’s officials detained before the Lord, etc.” In Yoel 1,14 we find the line קדשו יום, עצרו עצרה, “solemnize a fast, proclaim an assembly!” In Kings II 10,20 we find that Yehu proclaimed an assembly in honour of the Baal, [he meant to make sure that he could kill all those who would worship the Baal, which he succeeded in doing, eradicating this cult from Israel. Ed.] The invitation read: קדשו עצרה לבעל, “proclaim a holy assembly for the Baal.” It is in this sense that the Torah refers to the day following the seventh day of the Sukkot festival as Atzeret, an assembly for G’d, the pilgrims for the Sukkot festival to Jerusalem being detained there for an additional day. The joy on that day was to be a Torah inspired and oriented joy, akin to when David says in Psalms 149,2 ישמח ישראל בעושיו, “Israel rejoices in its Maker.”
We find that the description of the family dinners held in the home of Job’s children, his seven sons and three daughters, at set intervals such festive get togethers were held. On the day after the completion of these festivities their father would send word to them to sanctify themselves and rise early in the morning and offer burnt offerings to atone for the possibility that they might have been remiss and committed some misdemeanour which would have displeased their G’d. (Job 1,4-5)
On the seventh day after the Exodus from Egypt the Israelites took time out to sing a song of thanksgiving to G’d for their final delivery from the pursuing Egyptians. Subsequently, in commemoration of that occasion, the Torah decreed that this day become an עצרת, a day devoted to contemplation of the great miracle on that first occasion. (Compare Exodus 15,1 and Deuteronomy 16,8).
Again, on the fiftieth day after the Exodus when the Israelites in a great assembly at Mount Sinai spent the day contemplating their elevation to an almost supernatural people, this day was also subsequently observed as an עצרת, although in the Torah this day is never referred to as such. The reason why the Torah itself does not refer to this day as an עצרת may be the fact that shortly thereafter all the accomplishments of this day were lost and the Jewish people were even commanded to divest themselves of the “jewelry” they had worn in commemoration of that wonderful day. (Exodus 33,6)
We find that the description of the family dinners held in the home of Job’s children, his seven sons and three daughters, at set intervals such festive get togethers were held. On the day after the completion of these festivities their father would send word to them to sanctify themselves and rise early in the morning and offer burnt offerings to atone for the possibility that they might have been remiss and committed some misdemeanour which would have displeased their G’d. (Job 1,4-5)
On the seventh day after the Exodus from Egypt the Israelites took time out to sing a song of thanksgiving to G’d for their final delivery from the pursuing Egyptians. Subsequently, in commemoration of that occasion, the Torah decreed that this day become an עצרת, a day devoted to contemplation of the great miracle on that first occasion. (Compare Exodus 15,1 and Deuteronomy 16,8).
Again, on the fiftieth day after the Exodus when the Israelites in a great assembly at Mount Sinai spent the day contemplating their elevation to an almost supernatural people, this day was also subsequently observed as an עצרת, although in the Torah this day is never referred to as such. The reason why the Torah itself does not refer to this day as an עצרת may be the fact that shortly thereafter all the accomplishments of this day were lost and the Jewish people were even commanded to divest themselves of the “jewelry” they had worn in commemoration of that wonderful day. (Exodus 33,6)