For the 30 days before Pesach, we are not supposed to say "this is for Pesach," but rather "this is for Yom Tov." The source indicates that the prohibition applies especially to utterances regarding meat, i.e., "This meat is for Pesach."
What is the reason for this prohibition? Is it because it could be understood as a false declaration that the meat (or other stuff) is the real korban Pesach?
-What are the legal origins of this prohibition, and what level of force does it have? (Is it halacha, minhag, or just superstition? Whose minhag/superstition, and from where/since when?)
-Does the prohibition apply only to that exact expression ("this is for Pesach")--or to what types of expressions in general?