《左传·昭公·昭公九年》
日子在甲子乙卯，叫做忌日，国君撤除音乐，学乐的人停止演习，这是为了忌避的缘故。
辰在子卯，谓之疾日。君彻宴乐，学人舍业，为疾故也。
The days of jiazi, yi mao, are called avoid days, the sovereign cancels music, the music learners stop practicing, this is for the purpose of avoiding. 