Musar for Bava Kamma 198:25

ומאי שנא דנכו ואיסור דפטירי משום דלא צריכי למיגמר רבי חייא נמי לאו למיגמר קא בעי רבי חייא לפנים משורת הדין הוא דעבד כדתני רב יוסף (שמות יח, כ) והודעת להם זה

— It must therefore be said that the two things were to his<span class="x" onmousemove="('comment',' I.e., the owner of the animal. ');">³⁶</span> advantage, first that he did not let you eat a thing which was possibly forbidden, secondly that he restrained you from receiving payment which might possibly have been a misappropriation. It was stated: If a <i>denar</i> was shown to a money changer [and he recommended it as good] but it was subsequently found to be bad, in one Baraitha it was taught that if he was an expert he would be exempt but if an amateur he would be liable, whereas in another Baraitha it was taught that whether he was an expert or an amateur he would be liable. R. Papa stated: The ruling that in the case of an expert he would be exempt refers to such, e.g., as Dankcho and Issur<span class="x" onmousemove="('comment',' Two renowned money changers in those days. ');">⁴⁰</span> who needed no [further] instruction whatever, but who made<span class="x" onmousemove="('comment',' Lit., 'But where was their mistake; they made, etc. ');">⁴¹</span> a mistake regarding a new stamp at the time when the coin had just [for the first time] come from the mint. There was a certain woman who showed a <i>denar</i> to R. Hiyya and he told her that it was good. Later she again came to him and said to him, 'I afterwards showed it [to others] and they said to me that it was bad, and in fact I could not pass it.' He therefore said to Rab: Go forth and change it for a good one and write down in my register that this was a bad business. But why [should he be different from] Dankcho and Issur<span class="x" onmousemove="('comment',' V. p. 583. n. 8. ');">⁴²</span> who would be exempt because they needed no instruction? Surely R. Hiyya also needed no instruction? — R. Hiyya acted within the 'margin of the judgment,'<span class="x" onmousemove="('comment',' For the sake of equity and mere ethical considerations. [On this principle termed lifenim mi-shurath ha-din according to which man is exhorted not to insist on his legal rights. v. Herford, Talmud and Apocrypha, pp. 140, 280. That there was nothing Essenic in that attitude, but that it is a recognised principle in Rabbinic ethics has already been shown by Buchler, Types, p. 37.] ');">⁴³</span> on the principle learnt by R. Joseph: 'And shalt show them<span class="x" onmousemove="('comment',' Ex. XVIII, 20; the verse continues, the way wherein they must walk and the work. ');">⁴⁴</span> means

Shenei Luchot HaBerit