Ellicott: (26) His wife looked back from behind him.—In Oriental countries it is still the rule for the wife to walk behind her husband. As regards the method of her transformation, some think that she was stifled by sulphureous vapours, and her body subsequently encrusted with salt. More probably, the earthquake heaped up a mighty mass of the rock-salt, which lies in solid strata round the Dead Sea, and Lot’s wife was entangled in the convulsion and perished, leaving the hill of salt, in which she was enclosed, as her memorial. Salt cones are not uncommon in this neighbourhood, and the American Expedition found one, about forty feet high, near Usdum (Lynch, Report, pp. 183 et seq.). Entombed in this salt pillar, she became a “monument of an unbelieving soul” (
Wisdom of Solomon 10:7).
Haydock:
And his wife. As a standing memorial to the servants of God to proceed in virtue, and not to look back to vice or its allurements. (Challoner) —
His, Lot’s
wife. The two last verses might be within a parenthesis. —
Remember Lot’s wife, our Saviour admonishes us. Having begun a good work, let us not leave it imperfect, and lose our reward. (Luke xvii; Matthew xxiv.) —
A statue of durable metallic salt, petrified as it were, to be an eternal monument of
an incredulous soul, Wisdom x. 7. Some say it still exists. (Haydock) — God may have inflicted this temporal punishment on her, and saved her soul. (Menochius) — She looked back, as if she distrusted the words of the angel; but her fault was venial. (Tirinus)
Swedenborg (allegorical): AC 2453. Verse 26. And his wife looked back behind him, and she became a pillar of salt. “His wife looked back behind him,” signifies that truth turned itself away from good, and looked to doctrinal things; “and she became a pillar of salt,” signifies that all the good of truth was vastated. Truth is said to turn itself away from good, and to look to doctrinal things, when the man of the church no longer has at heart what kind of a life he lives, but what kind of a doctrine he possesses when yet it is a life according to doctrine that makes a man of the church, but not doctrine separate from life; for when doctrine is separated from life, then because good, which is of the life, is laid waste, truth, which is of doctrine, is also laid waste, that is, becomes a pillar of salt; which every one may know who looks only to doctrine and not to life, when he considers whether, although doctrine teaches them, he believes in the resurrection, in heaven, in hell, even in the Lord, and in the rest of the things that are of doctrine. [Do not believe only, but also live and act what doctrine teaches.]
These are just some sources interpreting it. The first more literal, the second more moral, the third more allegorical. Take them for what you will.