1 Kings 8:2

2And all the men of Israel assembled to King Solomon at athe feast in the month Ethanim, which is the seventh month.

1 Kings 8:65

65So Solomon held bthe feast at that time, and all Israel with him, a great assembly, from cLebo-hamath to dthe Brook of Egypt, before the Lord our God, seven days.
Septuagint; Hebrew  seven days and seven days, fourteen days

2 Chronicles 7:9

9And on the eighth day they held a solemn assembly, for they had kept the dedication of the altar seven days and the feast seven days.
Copyright information for ESV