The Torah commands in Parashat Vayikra, “Al Kol Korbancha Takrib Melah” – that salt must be added to every offering brought on the altar. This Misvat Aseh (affirmative command) comes in addition to the Misvat Lo Ta’aseh (prohibition) that forbids bringing an offering that does not include salt.
The Sefer Ha’hinuch offers two explanations for why the Torah requires adding salt to sacrificial offerings. First, everything that is done in the Bet Ha’mikdash is intended to create an aura which impacts and inspires those who come there, and to that end, the service in the Bet Ha’mikdash must appeal to all of a person’s senses. Adding salt to meat, the Sefer Ha’hinuch writes, enhances not only the taste of the meat, but also its aroma, and it thus contributes to creating a pleasing and impressive aura in the Bet Ha’mikdash.
The Sefer Ha’hinuch also suggests that salt acts as a preservative, preventing the food from rotting, and it is thus included with sacrifices to indicate to us that sacrifices have the effect of “preserving” a person. They have a spiritual impact upon the one who offers them, and thus protects him from “rotting” – meaning, from spiritual ruin. Salt is added so that the person offering the sacrifice will reflect on the value of the sacrifice, how it is acting to spiritually “preserve” him.
The Rambam, in Moreh Nebuchim (3:46), offers a different reason for this command, explaining that it is intended to oppose the practices of the idolaters. It is well-known, the Rambam writes, that the ancient pagans made a point of not adding salt to their offerings, and so the Torah requires us to do just the opposite, and specifically ensure to add salt to every offering placed on the altar. The Rambam explains other commands relevant to sacrifices in a similar manner. For example, he writes that the ancient pagans would smear their sacrifices with honey, and that they would bring elaborate breads as offerings, and for this reason, the Torah forbids offering leavened products or sweet food items as sacrifices.
Everything offered on the altar must have salt added to it, except the wine and water libations, the sacrificial blood that is sprinkled on the altar, and the wood placed on the altar to sustain the fire. An offering that was placed on the altar without salt is nevertheless valid, with the exception of the Minha (grain offering), which is invalid if salt is not added. The Torah commands that salt must not be withheld “Me’al Minhatecha” – “from upon your Minha,” indicating that this sacrifice, in particular, must include salt, and is invalid if salt is not added.
A Kohen who fails to add salt to an offering he places on the altar violates both a Misvat Aseh as well as a Misvat Lo Ta’aseh, and is liable to Malkut for transgressing the Misvat Lo Ta’aseh.
The Rabbis teach us that nowadays, when we do not have a Bet Ha’mikdash, the table in our home is considered our “altar.” Accordingly, a number of Poskim, including the Arizal (Rav Yishak Luria, Safed, 1534-1572) and the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), ruled that one should always keep salt on his table, and this has the power to “preserve” and protect us from harmful spiritual forces.