2 Chronicles 7:9
And in the eighth day they made a solemn assembly: for they kept the dedication of the altar seven days, and the feast seven days. And in the eighth day they made a solemn assembly: for they kept the dedication of the altar seven days, and the feast seven days.
2 Chronicles 7:9 belongs to the account of Solomon's temple dedication and concludes it by recording a solemn assembly on the eighth day after seven days for dedicating the altar and seven days for the feast. Its setting includes Solomon's dedication prayer, the sacrifices offered, and God's answer to Solomon's prayer. The temple was dedicated with great solemnity to the worship of God, who honored it with a visible manifestation of His presence, and the feast was held after Solomon's prayer and God's approval of the dedication.
In this dedication Solomon himself led the services, including sacrifices, prayer, consecration of the temple, and blessing the people. The priests appear as bearers of the ark, with no mention of the high priest. Solomon also continued to perform priestly duties at the annual feasts, offered incense, and assigned the priests their specific work, thus joining kingly and priestly roles in his own person.
The recorded observance of these seventh-month festivals shows that they were kept, even though the great Day of Atonement closely connected with them has no recorded instance of observance. That recorded keeping of the seven days of altar dedication, the seven days of feast, and the assembly on the eighth day shows that biblical silence about another sacred observance does not prove that it was not kept.