English: “Do not omit salt” — bring salt that does not cease; which is that? Sedom salt. And if Sedom salt is unavailable, one may bring Istrokianith. “Covenant” — just as the covenant stated elsewhere is from public funds, so here the salt is supplied by the public.
In Sifra: The ideal salt is the strong, non-vanishing salt of Sedom. The public treasury supplies it, parallel to other communal obligations tied to a “covenant.”
Type of Learning
R’ Eliezer #7 (גזירה שוה) on “beris” + procedural preference.
What Is Learned
Salt for the altar is a public obligation; Sedom salt is preferred, with a permitted substitute when necessary.