Shabbat 82

והלא מצרף ר' שמעון היא דאמר. דבר שאין מתכוין מותר מתקיף לה אביי מידי מיחם שפינה ממנו מים קתני מיחם שפינהו קתני

But does he not harden it?<span class="x" onmousemove="('comment',' Sc. The metal of the boiler, by pouring cold water into it while it is hot. This itself is forbidden on the Sabbath. ');">¹</span> — This agrees with R. Simeon, who ruled: That which is unintentional is permitted.<span class="x" onmousemove="('comment',' Supra 22a, 29b. ');">²</span>

אלא אמר אביי הכי קאמר המיחם שפינהו ויש בו מים חמין לא יתן לתוכו מים מועטין בשביל שיחומו אבל נותן לתוכו מים מרובים כדי להפשירן ומיחם שפינה ממנו מים לא יתן לתוכו מים כל עיקר מפני שמצרף ור' יהודה היא דאמר דבר שאין מתכוין אסור

Abaye demurred to this: Is it then stated, A BOILER from which the water IS REMOVED: Surely it is stated, IF A BOILER IS REMOVED? Rather said Abaye, this is the meaning: If a boiler is removed [from the fire] and it contains hot water, one must not pour therein a little water to heat it [the added water], but he may pour a large quantity of [cold] water therein to temper it.<span class="x" onmousemove="('comment',' I.e., reduce its heat. ');">³</span> But if the water is removed from a boiler, no water at all may be poured therein, because that hardens it; this agreeing with R. Judah, who maintains: [Even] that which is un-intentional is forbidden.

אמר רב ל"ש אלא להפשיר אבל לצרף אסור ושמואל אמר אפי' לצרף נמי מותר לצרף לכתחילה מי שרי אלא אי איתמר הכי איתמר אמר רב לא שנו אלא שיעור להפשיר אבל שיעור לצרף אסור ושמואל אמר אפ' שיעור לצרף

Rab said: They taught [that it is permitted] only to temper [the water]; but if it is to harden [the metal], it is forbidden. Whereas Samuel ruled: Even if to harden it, it is still permitted. If the primary purpose is to harden it, can it be permitted!<span class="x" onmousemove="('comment',' Surely not. ');">⁴</span> Rather if stated, it was thus stated: Rab said: They taught this only where there is [merely] a sufficient quantity to temper it; but if there is enough to harden it, it is forbidden.<span class="x" onmousemove="('comment',' Rashi; Rab explains the Mishnah as R. Adda b. Mattenah, viz., that the water was removed from the boiler. Thereon Rab observes: though a large quantity of water may be poured into it, it must nevertheless be insufficient to harden it, but merely enough to temper the water, i.e., it must not be completely filled with cold water, for that hardens the metal. Ri maintains that if the hot water is first emptied, even a small quantity of cold water poured into it immediately afterwards will harden it. Hence he interprets it thus: Rab explains the Mishnah as Abaye, as meaning that the boiler was removed with its hot water. Nevertheless, it must not be filled up with cold water, for that hardens it, as before. ');">⁵</span> Whereas Samuel maintained: Even if there is a sufficient quantity to harden it,