הלכה על סוטה 27:8

However we should not be called from the group of fools, in our spending all of our breath on [empty] words; as in much waste, a little food can sometimes be found. Also because we have seen our Rabbis, may their memory be blessed, saying [words] similar to our words: As they said about the sacrifice of a sotah (a suspect of adultery) (Sotah 14a), "She did an animal act, therefore she should bring barley (animal food)"; and with the sacrifice of a metsora (Vayikra Rabbah 16, Arakhin 16b), "He did an act of chatter, he should bring birds." And similar to this, they, may their memory be blessed, said regarding the matter of a menstruant woman, "Why did the Torah say that she sit seven clean days? That she be most dear to him." And in truth, none of all this is in their opinion the ultimate intent of the things. Rather, it is to inform that the matter of the commandment includes many hints, besides the great and strong fundamentals.