《旧唐书·本纪·卷六》
永昌元年春正月，神皇武则天亲自祭献明堂，大赦天下，改年号，大宴饮七天。
永昌元年春正月，神皇亲享明堂，大赦天下，改元，大酺七日。
In the spring of the first month of the first year of the Yongchang period, the Divine Sovereign Wu Zetian personally paid tribute to Mingtang Temple, granted amnesty to the world, changed the name of the year and held a great banquet for seven days.