Ecclesiastes Rabbah 9:13

¹“This, too, I have seen as wisdom under the sun; and it is great to me” (Ecclesiastes 9:13). “This, too, I have seen as wisdom under the sun…” Rabbi Shmuel bar Imi said: This is the thinking of the deceitful in their deceit, such as one who mixes water into wine, glaucium oil into [olive] oil, spring water into honey, donkey milk into balsam oil, sap into myrrh, vine leaves into pepper. One may not make a scale rod long on this side and short on that side; an instrument for leveling grain that is thick on this side and thin on that side; a scale rod or instrument for leveling that has a receptacle for metal; a rod that has a receptacle for money; the cane of a poor person with a receptacle for water; or a rod with a receptacle for a mezuza and a pearl – all these are ritually impure. Regarding all of them, Rabbi Yoḥanan said: Woe is me if I discuss [them], and woe is me if I do not discuss [them]. If I discuss them, I am teaching the swindlers [new techniques for swindling]. If I do not discuss [them], I am withholding knowledge and causing that which is ritually pure to become impure. Alternatively, [I should discuss them] so the swindlers will not think that the Sages are not well-versed in their actions. Rabbi Shmuel said: Nevertheless, “For the ways of the Lord are upright; the righteous will follow them and sinners will falter in them” (Hosea 14:10).