Bava Kamma — Daf 78a

והא גבי קדשים נמי נאמר שור או כשב שאין אתה יכול להוציא כלאים מביניהם ונרבי מדסיפא למעט רישא נמי למעט אדרבה מדרישא לרבות סיפא נמי לרבות

האי מאי אי אמרת בשלמא למעט הוא דאיצטריך תרי מיעוטי דאע"ג דאימעט כלאים איצטריך למעוטי נדמה אלא אי אמרת לרבות תרי ריבויי למה השתא כלאים אירבי ליה נדמה מבעיא

אלא הא דאמר רבא זה בנה אב כל מקום שנאמר שה אינו אלא להוציא את הכלאים למאי הלכתא אי לקדשים בהדיא כתיב בהו (ויקרא כב, כז) שור או כשב פרט לכלאים

אי למעשר תחת תחת יליף מקדשים

אי לבכור העברה העברה יליף ממעשר

אי נמי נדמה אמרת לא דכתיב (במדבר יח, יז) אך בכור שור עד שיהא הוא שור ובכורו שור כלאים מבעיא

אלא כי איתמר דרבא לענין פטר חמור כדתנן אין פודין לא בעגל ולא בחיה ולא בשחוטה ולא בטריפה ולא בכלאים ולא בכוי

ולרבי אלעזר דמתיר בכלאים דתנן ר"א מתיר בכלאים מפני שהוא שה למאי הלכתא

אמר לך ר"א כי איתמר דרבא לטמא שנולד מן הטהור ועיבורו מן הטמא ודלא כרבי יהושע דאי ר' יהושע משה כשבים ושה עזים נפקא ליה עד שיהא אביו כבש ואמו כבשה

וטהורה מטמאה מי מיעברא אין דקיי"ל

But in connection with sacrifices it is also written 'a bullock or a sheep', in which case it is impossible for you to exclude a hybrid born from these two, why then should we not employ the term 'or' to include [a hybrid of a different kind]? — Since the term 'or' in the later phrase  is to 'be employed to exclude, the term 'or' in the earlier phrase  should similarly be employed to exclude. But why not say on the contrary that, as the term 'or' in the earlier phrase has to be employed to amplify, so also should the term 'or' in the later phrase? — Would this be logical? I grant you that if you say that the term 'or' meant to exclude, then it would be necessary to have two [terms 'or'] to exclude, for even when a hybrid has been excluded, it would still be necessary to exclude an animal looking like a hybrid. But if you say it is meant to amplify, why two amplifications [in the two terms 'or']? For once a hybrid is included, what question could there be of an animal looking like a hybrid. To what halachah then would the statement made by Raba refer, that this is a locus classicus for the rule that wherever it says 'sheep'. the purpose is to exclude a hybrid? If to sacrifices, is it not explicitly said: 'A bullock or a sheep which excepts a hybrid'? If to the tithes [of animals], is not the term 'under'  compared to 'under' used in connection with sacrifices [making it subject to the same law]? If to a firstling, is the verb expressing 'passing'  not compared to 'passing'  used in connection with tithe? Or again we may say, since where the animal only looks like a hybrid you say that it is not [subject to the law of firstling], since it is written: 'But the firstling of an ox'  [which implies that the rule holds good] only where the parents were of the species of 'ox' and the firstling was of the species of 'ox', what question can there be regarding a hybrid itself? — The statement made by Raba must therefore have referred to the firstling of an ass,  as we have learnt:  It can not be redeemed either by a calf or by a wild animal or by a slaughtered sheep or by a trefa sheep or by a hybrid or by a koy.  But if we accept the view of R. Eleazar, who allows redemption with a hybrid sheep, as we have learnt: R. Eleazar allows the redemption to be made with a hybrid, for it is a sheep,  to what halachah [can we refer the statement of Raba]? — R. Eleazar might reply that the statement made by Raba is to teach [the prohibition of] an unclean animal  born from a clean animal  which became pregnant from an unclean animal [being forbidden as food].  this opinion not being in accordance with R. Joshua. for R. Joshua derived  this prohibition from the verse 'the sheep of sheep and the sheep of goats'.  which implies that unless the father was a 'sheep' and the mother a 'sheep' [the offspring is forbidden for food]. But could a clean animal become pregnant from an unclean animal? — Yes, since it is known to us