In Mosiah 5:4, the people preformed a Hosanna Shout during a Solemn Assembly:
“And it is the faith which we have had on the things which our king has spoken unto us that has brought us to this great knowledge, whereby we do rejoice with such exceedingly great joy.”
“Solemn assemblies are used for three purposes: the dedication of temples, special instruction to priesthood leaders, and sustaining a new President of the Church.”
said David B. Haight in 1994. King Benjamin got special instruction from God: a new covenant that every person old enough took upon themselves.