Speak to the children of Israel and say to them: When you come into the land to which I am bringing you.
Torah Temimah on בבואכם אל הארץ: entry of the whole people; challah in our time is rabbinic (Sifrei).
English: It is taught: “When you come into the land” — might “when you come” mean once two or three spies entered? The verse says “when you come” — the coming of all of you, not the coming of some of you. And from here: challah in the present time is rabbinic.
Collective entry requirement; status of challah outside full settlement.
Obligation of challah is keyed to the entry of the people as a whole; today’s practice outside the Temple order is by rabbinic extension.