וַֽיַּעֲשׂ֛וּ בַּיּ֥וֹם הַשְּׁמִינִ֖י עֲצָ֑רֶת כִּ֣י ׀ חֲנֻכַּ֣ת הַמִּזְבֵּ֗חַ עָשׂוּ֙ שִׁבְעַ֣ת יָמִ֔ים וְהֶחָ֖ג שִׁבְעַ֥ת יָמִֽים׃
And on the eighth day they held a solemn assembly; for they kept the dedication of the altar seven days, and the feast seven days.
Read halakhic rulings (Jewish law) on II Chronicles 7:9: and classical halakhic sources.