Melachim Alef 8:9-11
Orthodox Jewish Bible
9 There was nothing in the Aron except the two Luchot HaAvanim (Tablets of Stone), which Moshe placed there at Chorev, when Hashem cut a Brit with the Bnei Yisroel, when they came out of Eretz Mitzrayim.
10 And it came to pass, when the Kohanim were come out of the Kodesh, that the anan filled the Beis Hashem,
11 So that the Kohanim could not stand up to minister because of the anan; for the Kavod Hashem had filled the Beis Hashem.Read full chapter