In contrast to the above mentioned feast days, the solemn assembly also was convened for special days of fasting. When the locust plague threatened the land, Joel exhorted Israel to “sanctify a fast, call a solemn assembly. Gather the elders and all the inhabitants of the land to the house of the Lord your God; and cry to the Lord” (Joel 1:14; cf. 2:15).
Amos and Isaiah disparaged these solemn assemblies (among other things) as that which God could not endure (Isa 1:13; Amos 5:21), because the people did not do justice in the land. As Isaiah charged, “even though you make many prayers...your hands are full of blood” (Isa 1:15).
This word, עֲצָרָה, H6809, also occurs in Jeremiah 9:2 for “a company of treacherous men.”
International Standard Bible Encyclopedia (1915)
See Congregation; Fasts and Feasts; SOLEMN, SOLEMNITY.
is the KJV tr. of the difficult Heb. phrase, מִמּוֹעֵ֛ד, which occurs only in Zephaniah 3:18 and is tr. “festival” by the RSV which follows the LXX and Syr. VSS, and “appointed time” by the JPS. The term is common enough in the OT and usually denotes a place of meeting (Ps 74:8, et al.). It is used also for fixed or appointed dates or seasons (Gen 1:14, et al.). Several other variants of the term occur as in Joshua 20:9 and Isaiah 14:31, two other difficult texts. Apparently the word had various pronunciations and variations in semantic development in antiquity which accounts for the confused state of the VSS. There is simply no ground for the qualitative rendering of the KJV and so some meaning must be derived from the context of the Zephaniah passage. The whole passage (3:8-20) is a comfort to the faithful in Israel. Therefore, as with all such promises, it refers to the coming of the Messiah and the institution of His kingdom. A similar phrase appears in Daniel 8:19 in reference to the end of the Old Covenant, and so the passage in Zephaniah is to be understood. The tr. “solemn assembly” is not wholly without merit as long as the time of its appointment is maintained as the most important aspect of its meaning.