Menachos 7:6-8:1

Menachos 7:6

How do we know that one who commits to bring a thanksgiving offering may only bring it from the unconsecrated property? From Deuteronomy 16:2, which says, “You shall offer the Passover offering to Hashem your God from the flocks and the herds.” The Passover offering can only be brought from sheep and goats, so why does it mention flocks and herds? This is to make the Passover offering like all offerings that come from flocks and herds. Just as the Passover offering, which is obligatory, can be brought only from unconsecrated animals, so may anything obligatory only be brought from unconsecrated animals. Accordingly, once a person takes a vow to bring a thanksgiving offering or a peace offering, they become obligatory and can only be brought from unconsecrated animals. Libations in any circumstance can only be brought only from unconsecrated property (because they are offered on the altar and not eaten).

Menachos 8:1

All public and private flour offerings may be brought from produce grown in Israel or from produce grown elsewhere, from the new crop or from the old, except for the omer and the two Shavuos loaves, which are only brought from the new crop of grain grown in Israel. All flour offerings may only be brought from the choicest ingredients. Michmas and Mezonicha are the sources of the choicest fine flour, followed by Chafrayim, in the valley. Produce from anywhere in Israel was sufficient but they used to bring it from these places.