Salt

Boyd’s Bible Dictionary:

(sea product). Abundant in Palestine. Used with food and sacrificial offerings (Job 6:66Can that which is unsavory be eaten without salt? or is there any taste in the white of an egg? (Job 6:6); Lev. 2:1313And 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. (Leviticus 2:13); Num. 18:1919All the heave offerings of the holy things, which the children of Israel offer unto the Lord, have I given thee, and thy sons and thy daughters with thee, by a statute for ever: it is a covenant of salt for ever before the Lord unto thee and to thy seed with thee. (Numbers 18:19); Mark 9:4949For every one shall be salted with fire, and every sacrifice shall be salted with salt. (Mark 9:49)). Monument of divine displeasure (Gen. 19:2626But his wife looked back from behind him, and she became a pillar of salt. (Genesis 19:26)); token of indissoluble alliance (Lev. 2:1313And 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. (Leviticus 2:13); Num. 18:1919All the heave offerings of the holy things, which the children of Israel offer unto the Lord, have I given thee, and thy sons and thy daughters with thee, by a statute for ever: it is a covenant of salt for ever before the Lord unto thee and to thy seed with thee. (Numbers 18:19); 2 Chron. 13:55Ought ye not to know that the Lord God of Israel gave the kingdom over Israel to David for ever, even to him and to his sons by a covenant of salt? (2 Chronicles 13:5)); used to rub new-born children (Ezek. 16:44And as for thy nativity, in the day thou wast born thy navel was not cut, neither wast thou washed in water to supple thee; thou wast not salted at all, nor swaddled at all. (Ezekiel 16:4)); type of maintenance (Ezra 4:1414Now because we have maintenance from the king's palace, and it was not meet for us to see the king's dishonor, therefore have we sent and certified the king; (Ezra 4:14) marg.); emblem of sterility (Judg. 9:4545And Abimelech fought against the city all that day; and he took the city, and slew the people that was therein, and beat down the city, and sowed it with salt. (Judges 9:45); Jer. 17:66For he shall be like the heath in the desert, and shall not see when good cometh; but shall inhabit the parched places in the wilderness, in a salt land and not inhabited. (Jeremiah 17:6)); a manure (Luke 14:3535It is neither fit for the land, nor yet for the dunghill; but men cast it out. He that hath ears to hear, let him hear. (Luke 14:35)); emblem of holy life and conversation (Matt. 5:1313Ye are the salt of the earth: but if the salt have lost his savor, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men. (Matthew 5:13); Mark 9:5050Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another. (Mark 9:50); Col. 4:66Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man. (Colossians 4:6)).

Concise Bible Dictionary:

The Christian’s speech should be with grace, seasoned with salt (Col. 4:66Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man. (Colossians 4:6)), not characterized by asperity, nor lacking unction, and yet morally wholesome in its character. “Everyone shall be salted with fire, and every sacrifice shall be salted with salt” (Mark 9:4949For every one shall be salted with fire, and every sacrifice shall be salted with salt. (Mark 9:49)). God puts all to the proof, but with the saint it is the dross that is consumed. Every sacrifice being salted with salt refers to the preservation of that which is set apart for God from corruption and impurity.
To “eat the salt” of their masters, is used by the Persians and Hindoos to imply that they are fed by their employers. This idea is found in Ezra 4:1414Now because we have maintenance from the king's palace, and it was not meet for us to see the king's dishonor, therefore have we sent and certified the king; (Ezra 4:14), where the opposers of the Jews say, “We eat the salt of the palace,” as the passage is more literally translated: see margin. With reference to an infant being “salted” (Ezek. 16:44And as for thy nativity, in the day thou wast born thy navel was not cut, neither wast thou washed in water to supple thee; thou wast not salted at all, nor swaddled at all. (Ezekiel 16:4)), Galen records that this was done to render the skin tighter and firmer.

“150. Use of Salt” From Manners and Customs of the Bible:

The reason for this law, according to Maimonides, was found in the fact that the heathen never offered salt in sacrifices. If this were the case in the time of Moses, their custom must have changed subsequently, since there is abundant evidence of this use of salt among heathen of a later day. Some suppose that they imitated in this the Jewish sacrifices.
The partaking of salt by different persons together is regarded among the Arabs as a pledge of friendship. It is equivalent to a most solemn covenant. Numerous instances are recorded by travelers illustrative of this. So deeply rooted is this sentiment, that intended robbery has been abandoned when the robber has accidentally eaten salt while getting his plunder. Travelers have sometimes secured their safety in the midst of wild Bedouin by using stratagem in getting the Arabs to eat salt with them. Macgregor tells how he thus outwitted a sheikh who had made him a prisoner, and whose disposition seemed to be unfriendly. “We had now eaten salt together, and in his own tent, and so he was bound by the strongest tie, and he knew it” (The Rob Roy on the Jordan, p. 260).

“637. Savorless Salt” From Manners and Customs of the Bible:

Matthew 5:1313Ye are the salt of the earth: but if the salt have lost his savor, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men. (Matthew 5:13). If the salt have lost his savor, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.
Salt produced by the evaporation of sea-water in hot countries is said sometimes to lose its saline properties. The same result is also sometimes seen in impure rock-salt that has long been exposed to the air. When such is the case there can nothing be done with it but to throw it out into the highway, where men and beasts trample it down. Dr. Thomson tells of some salt which was brought from the marshes of Cyprus by a merchant of Sidon, and stored in small houses with earthen floors. “The salt next the ground in a few years entirely spoiled. I saw large quantities of it literally thrown into the street, to be trodden under foot of men and beasts. It was good for nothing” (The Land and the Book, vol. 2, p. 43).
Schöttgen supposes reference is here made to the bituminous salt from the Dead Sea, which, he says, was strewn over the sacrifices in the temple to neutralize the smell of the burning flesh, and when it became spoiled by exposure it was cast out upon the walks to prevent slipping in wet weather, and was thus literally “trodden under foot of men.”