Midrash su Ecclesiaste 9:6

Rabbi taught to R. Simon his son: Acherim say: "If it were an exchange (Fol. 14) it would be sacrificed." Whereupon R. Simon interrupted him and said: "Who are they whose water (Torah) we drink and whose names we do not mention?" And he answered: "They were the men who conspird to destroy your glory and that of your father's house." R. Simon then quoted the passage (Ecc. 9, 6) Also their love, and their hatred, and their envy are now already lost. Whereupon his father quoted the following (Ps. 9, 7) The enemy is lost, but his ruinous deeds are still existing. R. Simon then said: "This would be right if the deeds of the Rabbis in question remained effective, but they whom you have in view had only an intention, for they were never realized." Thereupon Rabbi taught to him again: "It was said in the name of R. Mair that if it were an exchange [for the original sacrificial animal] it could not be offered on the altar. To this Raba made the following remark: "Rabbi, though modest in nature, yet refrained from saying, 'It was said by R. Mair,' but taught it was said in the name of R. Mair."