Zevachim Daf 66 זבחים דַף 66

A Baraisa darshens an extra word "עולה" to teach: אף על פי שמיצה דם הגוף ולא מיצה דם הראש – even if the Kohen squeezed out the blood of the body (of the עולת העוף) but did not squeeze out the blood of the head, it is valid. One might have validated the korban even where he squeezed out only the blood of the head and not of the body, so the passuk says "הוא" – it is (implying some other case of עולה is invalid). Ravina explains why it is the blood of the body, and not the head, which is מעכב: מסתברא דרוב דמים בגוף שכיחי – it is reasonable, because most of the blood is found in the body, rather than the head.

The seventh Perek begins: חטאת העוף שעשאה למטה – a bird-chatas which one [offered] below (theחוט הסיקרא), כמעשה חטאת לשם חטאת – performing the chatas procedure (i.e., מליקה of one siman, הזאה, and מיצוי), for the sake of chatas, it is valid. However, if he performed the חטאת procedure לשם עולה, or did כמעשה עולה – the olah procedure (which the Gemara will explain means he was מבדיל, doing מליקה of both סימנים) for the sake of חטאת, or did the עולה procedure לשם עולה, these are all invalid. If he offered it above the חוט הסיקרא, in all cases (even כמעשה חטאת לשם חטאת), it is invalid, since a חטאת העוף must be brought למטה (this refers to blood applications, whereas מליקה is valid anywhere on the מזבח). An עולת העוף which was brought above (the חוט הסיקרא), כמעשה עולה לשם עולה – like the olah procedure (i.e., מליקה of both סימנים, and with הזאה), for the sake of olah, it is valid. If it was brought לשם חטאת, it is valid, but does not fulfill the owner’s obligation (like any עולה brought שלא לשמה). If it was brought כמעשה חטאת (i.e., he sprinkled the blood instead of squeezing it out), it is invalid. If it was brought below, it is invalid in all cases.

The next Mishnah states that all the birds in the previous Mishnah are not metamei בבית הבליעה – through the throat, like a נבילה of a kosher bird normally is, because a מליקה of a korban, even an invalidated one, purifies it from tumah. All these cases are subject to me’ilah, except for a חטאת העוף performed properly, which becomes permitted for Kohanim to eat. If an עולת העוף was offered למטה כמעשה חטאת לשם חטאת – below, like the chatas procedure (i.e., only one siman was cut through מליקה), Rebbe Eliezer says מועלין בה – one transgresses me’ilah through misusing it, but Rebbe Yehoshua says אין מועלין בה. Rebbe Eliezer challenged him: if a חטאת, which is not subject to me’ilah when brought לשמה (since it is eaten), is still subject to me’ilah כששינה את שמה – when he changed its purpose (i.e., brought it as an עולה), then an עולה, which is subject to me’ilah when brought properly (since it is not eaten), certainly should be subject to me’ilah when it was brought as a חטאת!? Rebbe Yehoshua replied that he cannot compare a חטאת changed to an עולה, which itself does have me’ilah, with the case of an עולה changed to a חטאת, since a חטאת is not subject to me’ilah. This discussion continues on the next Daf.