Midrash su Levitico 27:9

1) (Vayikra 27:9) ("And if it be a beast, of which men present an offering to the L–rd, all that he gives of it to the L–rd shall be holy.") If one said "The leg of this animal is a burnt-offering," I might think that the entire animal becomes a burnt-offering; it is, therefore, written "all that he gives of it to the L–rd shall be holy" — but all of it is not holy. I might then think that the animal becomes chullin (non-sacred); it is, therefore, written "shall be" — it retains its holiness. What shall he do? He sells it to those who must bring a burnt-offering, and its monies become chullin, except for (the monies for) that foot. These are the words of R. Meir. R. Yehudah, R. Yossi, and R. Shimon say: Whence is it derived that even if he said "Its foot is a burnt-offering," all of it becomes a burnt-offering? From "all that he gives of it to the L–rd shall be holy" — "shall be holy," to include all of it.

2) I might think that dedications to Temple maintenance (bedek habayith) are (also) susceptible of substitution (viz. Vayikra 27:10) it is, therefore, written "offering" — to exclude dedications to Temple maintenance, which are not offerings.

3) I would then exclude dedications to Temple maintenance, which are not offerings, but I would not exclude communal dedications (of offerings); it is, therefore, written (Vayikra 27:10) "He shall not exchange it." I would then exclude communal offerings, but I would not exclude offerings in partnership; it is, therefore, written (again) "and he shall not substitute for it" — An individual can make a substitution, but not the community or partners.