《礼记·祭义》
孝子将要举行祭祀，有关的事情不可不提前考虑；届时，一切物品都要置办齐备；在做这些准备工作时，心中不可有其它杂念。
孝子将祭，虑事不可以不豫；比时具物，不可以不备；虚中以治之。
When a filial son sacrifices, matters which concern the sacrifice cannot be thought of at first; at that time, all the objects must be well prepared; when making these preparations, there should be no other thoughts in the heart.