The Torah's own command establishes salt as integral to korbanos: every minchah must be salted, and salt is described as the eternal 'covenant of your God' that must never cease from the offering (Vayikra 2:13), and the same covenantal language of an eternal 'covenant of salt' appears regarding the priestly gifts (Bamidbar 18:19, Targum Jonathan on Bamidbar 18:19). The Sifra clarifies the technical requirement that the salt be of moderate grain, specifically Sodomite salt that does not dissolve away (Sifra, Vayikra Dibbura DeNedavah, Chapter 14:4), and the Gemara extends the salt requirement even to the wood offering under Rabbi Yehuda HaNasi's view that it is treated like a minchah (Menachot 20b:3-4).
Chazal transfer this altar-symbolism directly onto the home table: since the destruction, a person's table atones for him the way the altar once did, drawing on the verse 'this is the table that is before the Lord' (Berakhot 55a:3), a reading echoed by Mishnah Berurah 167:30 and Rabbeinu Bachya.
The halachic codes make the practical consequence explicit: the Rema rules that it is a mitzvah to place salt on every table before breaking bread, because the table resembles the altar and the eating resembles a korban, invoking 'al kol korbanecha takriv melach,' and he adds that the salt guards against misfortune (Shulchan Arukh, Orach Chayim 167:5), a ruling the Beit Yosef, Orach Chayim 167:9 traces to Rabbeinu Menachem's practice of being especially careful to bring salt to the table. The Tur, Orach Chayim 167 situates this within the broader laws of how the bread is cut and blessed, and later authorities such as Kitzur Shulchan Arukh Yalkut Yosef, Orach Chaim 180:3, Kitzur Shulchan Arukh Yalkut Yosef, Orach Chaim 167:8, Kaf HaChayim on Shulchan Arukh, Orach Chayim 608:30:1, Kaf HaChayim on Shulchan Arukh, Orach Chayim 167:40:1, and Peri Megadim on Orach Chayim, Eshel Avraham 167:15:1 preserve and extend this practice, including keeping the salt present until after bentching.
The meforshim on the pasuk itself develop the deeper meaning of salt beyond the sacrificial mechanics. Rashi explains that the covenant was forged with salt from the six days of creation, when the lower waters were promised to be offered via salt on the altar and the water libation of the festival (Rashi on Vayikra 2:13). The Ramban develops salt as a symbol combining water and fire, representing the totality of divine middos and the enduring dominion of Hashem, like salt that gives lasting flavor (Ramban on Vayikra 2:13), while Rav Samson Raphael Hirsch explains salt as representing unchanging permanence that guards the covenant against external influence, fitting the very concept of a covenant that is set apart and unaffected by change (Rav Samson Raphael Hirsch, Rav Samson Raphael Hirsch). Rabbeinu Bahya focuses on the technical point that the salt must be of a middling consistency, paralleling how we salt meat today (Rabbeinu Bahya, Vayikra 2:13:1).
Kabbalistic and chassidic sources add a further symbolic layer in which salt represents the attribute of judgment that must be sweetened. Rav Eliezer Melamed (Peninei Halakhah, Berakhot 3:5) explains that bread represents the attribute of mercy that sustains life, while salt represents harsh judgment, and dipping bread into salt sweetens the judgment by making it subordinate to the mercy of the bread. The Sulam on the Zohar similarly explains that salt purifies and sweetens the bitterness of the left side's judgments by blending them with the mercy of the right side, so that the world can bear what would otherwise be unbearable severity (Sulam on Zohar, Vayechi 666), and the Zohar itself links the inauguration of the Mishkan's service to an offering brought as a meal (Zohar, Vayikra 2). The Shenei Luchot HaBerit brings Rabbeinu Menachem's teaching that bringing salt to the table protects diners from the Satan's accusation while they wait for one another to wash before the meal (Shenei Luchot HaBerit, Shaar HaOtiyot, Kedushat HaAchilah, Maachalot Asurot 7:24), and the Tanya discusses how physical eating, even of rich food, can be elevated into holiness when directed toward divine service (Tanya, Part I; Likkutei Amarim 7:3-4).
Later poskim transmit and apply this symbolism in practical halachah. Rav Mordechai Eliyahu records the custom of dipping bread in salt three times, corresponding kabbalistically to three expressions of Divine Name sweetening three expressions of severity, and rules that the salt should remain on the table until after bentching since the table resembles the altar (Rav Mordechai Eliyahu (Shut HaRav HaRashi 15:64), Rav Mordechai Eliyahu (Maamar Mordechai Hilchot Shabbat, Chelek 1 20:44), Rav Mordechai Eliyahu (Maamar Mordechai Hilchot Shabbat, Chelek 1 20:43)).
Other sources tie the table's symbolism to related vessels of the Mikdash: the Tur HaArokh connects the showbread table to blessing and sustenance flowing to Israel (Tur HaArokh, Shemot 25:23), and the Kad HaKemach contrasts the table and menorah as symbols of physical and spiritual sustenance that depend on each other (Kad HaKemach, Groom 2:3).
Mishneh Halachos (Mishneh Halachos 10:322) likewise ties placing salt on the table to the meal functioning as an altar, invoking 'al kol korbanecha takriv melach' and describing salt as embodying both mercy and judgment, alongside related discussion of the pause before eating and the water libation.
Teshuvos V'hanhagos (Teshuvos V'hanhagos 4:50) holds that bread is not considered properly accompanied for the hamotzi blessing without salt or another relish, grounding the custom of salt in the table's comparison to the altar and the same verse, while noting that dipping in salt is a kabbalistic enhancement rather than a strict requirement.
Az Nidberu (Az Nidberu 8:48) rules that salt should be brought to every table because it protects against misfortune, citing the teaching that Israelites waiting for one another to wash hands before eating are vulnerable to the Satan's accusation absent an accompanying mitzvah.
Rav Menashe Klein (Mishneh Halachos 10:48) gathers several of these threads together, explaining that salt on the table symbolizes the altar and the offering, guards against the Satan's accusation during the wait to wash hands, reflects the interplay of mercy and judgment, recalls the future role of the lower waters in offerings, and signifies Torah study and communal patience at the table.