Albert Barnes Commentary 1 Kings 8:2

"And all the men of Israel assembled themselves unto king Solomon at the feast, in the month Ethanim, which is the seventh month." — 1 Kings 8:2 (ASV)

The feast in the month Ethanim - that is, the Feast of Tabernacles, or the Feast of Ingathering. This feast was a commemoration of the dwelling in booths at the time of the Exodus and a festival of thanksgiving for the completion of the harvest (Exodus 23:16; Leviticus 23:39; Deuteronomy 16:13). It was one of the three festivals at which the people were required to “appear before the Lord.”