'Solemn Assembly' in the Bible

“On the eighth day you are to hold a solemn assembly; you are not to do any daily work.

You must eat unleavened bread for six days. On the seventh day there is to be a solemn assembly to the Lord your God, and you must not do any work.

Jehu commanded, “Consecrate a solemn assembly for Baal.” So they called one.

If only I had a traveler’s lodging placein the wilderness,I would abandon my peopleand depart from them,for they are all adulterers,a solemn assembly of treacherous people.