'Solemn Assembly' in the Bible

Jehu ordered, "Set aside a solemn assembly for Baal!"

On the day after the festival ended, they convened a solemn assembly, because they had been dedicating the altar for seven days and observing the festival for seven days.

and Ezra continued to read from the Book of the Law of God day by day, from the first day through the last. They celebrated for seven days, and on the eighth day they held a solemn assembly according to regulation.

Stop bringing useless offerings! Incense is detestable to me, as are your New Moons, Sabbaths, and calling of convocations. I cannot stand iniquity within a solemn assembly.

Set apart time for a fast! Call a solemn assembly! Gather the elders and everyone living in the land to the Temple of the LORD your God, and cry out to the LORD!"

"Sound the ram's horn in Zion! Dedicate a fast and call for a solemn assembly!

I will gather the afflicted from the solemn assembly; those who were with you, who were bearing a burden of disgrace.