Genesis 19:26 - Matthew Poole's English Annotations on the Holy Bible

His wife looked back, through curiosity, or unbelief, or desire of what she left, or from all these causes; from behind her husband, whom she followed. Which circumstance seems to be mentioned as the reason of this presumption, because she could do it without her husband's observation or reproof, to which she had a greater regard than to the all-seeing eye of God. And she, i.e. her body, by a very common synecdoche, became a pillar of salt; either metaphorically, i.e. a perpetual durable pillar, as an everlasting covenant is called a covenant of salt, Numbers 18:19; or properly, for there is a kind of metallic salt which resists the rain, and is hard enough for buildings, as Pliny, Solinus, and others witness. And that salt was here mixed with brimstone, may be gathered from Deuteronomy 29:23. Add to this, that Josephus, Antiq. i. 12, affirms that this pillar remained in his time. And the like is witnessed by others after him.