When Solomon had finished all the work related to building the Temple of the LORD, he brought in the gifts dedicated by his father, King David, including all the silver and gold and all the utensils. These were stored in the treasuries of the Temple of God.
Solomon then summoned the leaders of all the tribes and families of Israel to assemble in Jerusalem. They were to bring the Ark of the LORD's covenant from its location in the City of David, also known as Zion, to its new place in the Temple.
They all assembled before the king at the annual Festival of Shelters in early autumn.
References for 2 Chronicles 5:3
When all the leaders of Israel arrived, the Levites moved the Ark,
along with the special tent and all its sacred utensils. The Levitical priests carried them all up to the Temple.
References for 2 Chronicles 5:5
King Solomon and the entire community of Israel sacrificed sheep and oxen before the Ark in such numbers that no one could keep count!
Then the priests carried the Ark of the LORD's covenant into the inner sanctuary of the Temple -- the Most Holy Place -- and placed it beneath the wings of the cherubim.
The cherubim spread their wings out over the Ark, forming a canopy over the Ark and its carrying poles.
These poles were so long that their ends could be seen from the front entrance of the Temple's main room -- the Holy Place -- but not from outside it. They are still there to this day.
Nothing was in the Ark except the two stone tablets that Moses had placed there at Mount Sinai, when the LORD made a covenant with the people of Israel after they left Egypt.
References for 2 Chronicles 5:10
Then the priests left the Holy Place. All the priests who were present had purified themselves, whether or not they were on duty that day.
And the Levites who were musicians -- Asaph, Heman, Jeduthun, and all their sons and brothers -- were dressed in fine linen robes and stood at the east side of the altar playing cymbals, harps, and lyres. They were joined by 120 priests who were playing trumpets.
The trumpeters and singers performed together in unison to praise and give thanks to the LORD. Accompanied by trumpets, cymbals, and other instruments, they raised their voices and praised the LORD with these words: "He is so good! His faithful love endures forever!" At that moment a cloud filled the Temple of the LORD.
The priests could not continue their work because the glorious presence of the LORD filled the Temple of God.