Pesachim 137
תניא אמר רבי אליעזר ומה לי אם דחו מכשירי מצוה שלאחר שחיטה את השבת דאיתעביד ליה מצוה לא ידחו מכשירי מצוה שלפני שחיטה את השבת
It was taught. R. Eliezer said: I argue, if the necessary adjuncts of the precept which [come] after shechitah, when the precept has [already] been performed, override the Sabbath; shall not the necessary adjuncts of the precept which [come] before shechitah override the Sabbath! Said R. Akiba to him: If the necessary adjuncts of the precept which [come] after shechitah override the Sabbath, the reason is because the shechitah has [already] overridden the Sabbath; will you say that the necessary adjuncts of the precept before the shechitah shall override the Sabbath, seeing that the shechitah has not [yet] overridden the Sabbath? Another argument is: the sacrifice may be found to be unfit, and thus he will be found retrospectively to have desecrated the Sabbath. If so, let us not slaughter it either, lest the sacrifice be found unfit, and thus it be found that he retrospectively desecrated the Sabbath? - Rather, he first told him this [argument], and he refuted it; and then he told him this 'the reason is etc.
אמר לו ר' עקיבא דמה לי אם דחו מכשירי מצוה שלאחר שחיטה את השבת שהרי דחתה שחיטה את השבת תאמר ידחו מכשירי מצוה שלפני שחיטה את השבת שלא דחתה שחיטה את השבת דבר אחר שמא ימצא זבח פסול ונמצא מחלל את השבת למפרע
be studied by day and by night, heaven and earth would not enjoy permanence. How then could R. Shesheth take such a selfish view of his studies? R. AKIBA ANSWERED AND SAID: LET HAZAAH PROVE IT etc. It was taught, R. Eliezer said to him: 'Akiba, you have refuted me by shechitah,' by shechitah shall be his death!' Said he to him 'Master, do not deny me at the time of argument: I have thus received [the law] from you. [vis.] haza'ah is a shebuth and does not override the Sabbath.' Then since he himself had taught it to him, what is the reason that he retracted? - Said 'Ulla: When R. Eliezer taught it to him it was concerning haza'ah for [the sake of] terumah, since terumah itself does not override the Sabbath; [and] R. Akiba too, when he refuted him refuted him by haza'ah for [the sake of] terumah, which is [likewise] a religious duty and is [usually forbidden] as a shebuth; but he [R. Eliezer] thought that he was refuting him by haza'ah for the Passover sacrifice. <br>
אי הכי משחט נמי לא נשחט שמא ימצא זבח פסול ונמצא מחלל את השבת למפרע אלא הא אמר ליה ברישא ופרכיה והדר א"ל הך דמה לי אם דחו:
Rabbah raised an objection:R.Akiba answered and said, Let the haza'ah of a person unclean through the dead prove [refute] it, - when his seventh [day] falls on the Sabbath and on the eve of Passover, so that it is a religious duty and it is [only] a shebuth, yet it does not override the Sabbath. Hence he [R. Eliezer] certainly taught him about haza'ah for [the sake of] the Passover sacrifice. Then since he [himself] had taught it to him what is the reason that R. Eliezer rebutted him [thus]? - R. Eliezer had forgotten his own tradition, and R. Akiba came to remind him of his tradition. Then let him tell it to him explicitly? - He thought that it would not be mannerly. <br>
השיב ר"ע ואמר הזאה תוכיח וכו': תניא אמר לו ר' אליעזר עקיבא בשחיטה השבתני בשחיטה תהא מיתתו אמר לו ר' אל תכפירני בשעת הדין כך מקובלני ממך הזאה שבות היא ואינה דוחה את השבת
Now, what is the reason that haza'ah does not override the Sabbath; consider, it is mere handling, [then] let it override the Sabbath on account of the Passover sacrifice? - Said Rabbah, It is a preventive measure, lest he take it [the water of purification] and carry it four cubits in public ground. But according to R. Eliezer, let us [indeed] carry it, for R. Eliezer ruled, The necessary adjuncts to a precept override the Sabbath? I will tell you: that is only when the man himself is fit [to perform the precept] and the obligation lies upon him; but here that the man himself is not fit, the obligation does not lie upon him.
וכי מאחר דהוא אגמרי' מאי טעמא קא הדר ביה אמר עולא רבי אליעזר כי אגמריה הזאה דתרומה אגמריה דתרומה גופה לא דחיא שבת
Rabbah said: According to the words of R. Eliezer, [if there is] a healthy infant, one may heat water for him to strengthen him and to circumcise him on the Sabbath, since it is fit for him. [If there is] a sickly infant, one may not heat hot water for him to strengthen him and to circumcise him, since it is not fit for him. Said Raba: But if he is healthy, why does he need hot water to strengthen him? Rather, said Raba, all are regarded as invalids in respect to circumcision: both in the case of a strong infant or a sickly infant, one may not heat hot water for him to strengthen him and to circumcise him on the Sabbath, since it is not fit for him.
ר"ע נמי כי אותביה הזאה דתרומה אותביה שהיא מצוה והיא משום שבות והוא סבר הזאה דפסח קא מותיב ליה
Abaye raised an objection against him: An [adult] uncircumcised person who did not circumcise himself [on the eve of Passover] is punished by kareth: this is the view of R. Eliezer. Now here, though the man himself is unfit, yet he states that he is punished by kareth, which proves that the obligation lies upon him. - Said Rabbah: R. Eliezer holds, One may not slaughter [the Passover] and sprinkle [its blood] for him who is unclean through a reptile,<br>