《礼记·杂记下》
女子虽未许嫁，到了二十岁时也要行异礼。为她行异礼时，在家找个妇人就行了，不须另请女宾。
女虽未许嫁，年二十而笄，礼之，妇人执其礼。
Even though the girl has not yet been engaged, when she reaches twenty years of age she must also perform the yili. When performing the yili for her, inviting a woman to perform the rite at home is sufficient, it is not necessary to invite another female guest.