Arachin 5a — ערכין ה.

"…'The foot of this animal is an (korban) olah.' We might think the whole animal becomes an olah."

"So the Torah says in Parshat Bechukotai, 'whatever he gives of it to Hashem shall be kodesh.' Of it, a part, is kodesh, and not all of it."

"We might think the rest goes out to chullin." The Rashash explains that this means by being redeemed.

"So the Torah says 'shall be': it stays as it is." Rabbeinu Gershom explains that it stays in its kedushah.

"How does this work? The animal is sold to someone who needs an olah, and the money is chullin, except the value of that one limb. These are the words of Rabbi Meir." Rashi explains that the buyer brings it as his olah, and only the money for the limb goes to hekdesh. He then asks how the buyer can offer an olah with a limb that is not his own, and points to Temurah 11b for the answer.

"Rabbi Yehuda, Rabbi Yose and Rabbi Shimon say: where do we learn that one who says 'the foot of this animal is an olah' makes all of it an olah?"

"The Torah says 'whatever he gives of it to Hashem shall be kodesh,' to include all of it."

And even according to Rabbi Meir, who says not all of it becomes an olah, that is when he made hekdesh a limb a person can live without. Rashi explains, from Temurah 11b, that they argue only about such a limb, like the leg below the knee.

But with a limb that life depends on, like the head, the whole animal becomes kodesh. So why does hekdesh get only the cow's head?

There is no contradiction. (Rashi reads this line without the word "ela.") Here, where all of it becomes kodesh, he gave it kedushat haguf: the animal itself is sanctified to be offered. There, where hekdesh has only the head, he gave it kedushat damim: only its value is sanctified, to buy a korban with that money. Rabbeinu Gershom explains that with kedushat damim, the head can be sold by itself, so only the head is hekdesh. With kedushat haguf, the head cannot be slaughtered as an olah while the body is slaughtered as chullin, since chullin may not be slaughtered in the azarah, so the kedushah spreads through all of it.

Abaye asks: but the Master himself said that one who makes a male animal hekdesh for its value gives it kedushat haguf! Rashi explains, from Temurah 11b, that a ram fit for an olah, made hekdesh for the value of an olah, becomes holy itself and is offered, because it is fit for the mizbe'ach. So here too, the cow's head for the value of an olah should become kedushat haguf and spread through the whole cow.

There is no contradiction. There he made all of the animal hekdesh, and here he made one limb hekdesh. Rashi explains that to go from one limb's kedushat damim to kedushat haguf on the whole animal would take two steps of "migo" (since this is true, that is true too), and we do not make two such steps.

The Gemara asks: but one limb is itself a question we asked!

Rabbah asked: if he made one limb hekdesh for its value, what is the law? Does the whole animal become kedushat haguf? So the baraita cannot be brought as a clear ruling.

Our question was about a tam, an animal without a mum, which is fit for the mizbe'ach.

Here the baraita is about a ba'al mum, an animal with a mum, like the donkey in the same baraita, which cannot be offered.

The Gemara asks: a ba'al mum was also a question we asked!

Rabbah asked: if a person pledges his head's value to the mizbe'ach, what is the law? Is he judged by his kavod or not? Rabbeinu Gershom explains that there is no greater ba'al mum for the mizbe'ach than a person.

That question came before we knew this baraita.

Once we know it, the question falls away, since the baraita shows that a ba'al mum for the mizbe'ach is not judged by his kavod.