leviticus 2:13 And every oblation of thy meat offering shalt thou season with salt; neither shalt thou suffer the salt of the covenant of thy God to be lacking from thy meat offering: with all thine offerings thou shalt offer salt. - Free Bible Online

      13. every . . . meat offering shalt thou season with salt--The same reasons which led to the prohibition of leaven, recommended the use of salt--if the one soon putrefies, the other possesses a strongly preservative property, and hence it became an emblem of incorruption and purity, as well as of a perpetual covenant--a perfect reconciliation and lasting friendship. No injunction in the whole law was more sacredly observed than this application of salt; for besides other uses of it that will be noticed elsewhere, it had a typical meaning referred to by our Lord concerning the effect of the Gospel on those who embrace it (Mr 9:49, 50); as when plentifully applied it preserves meat from spoiling, so will the Gospel keep men from being corrupted by sin. And as salt was indispensable to render sacrifices acceptable to God, so the Gospel, brought home to the hearts of men by the Holy Ghost, is indispensably requisite to their offering up of themselves as living sacrifices [BROWN].

JFB.