John Wesley on Genesis 19:26

But his wife looked back from behind him - Herein she disobeyed an express command. Probably she hankered after her house and goods in Sodom, and was loath to leave them. Christ intimates this to be her sin, Luke 17:31,32, she too much regarded her stuff. And her looking back spoke an inclination to go back; and therefore our Saviour uses it as a warning against apostasy from our Christian profession. And she became a pillar of salt - She was struck dead in the place, yet her body did not fall down, but stood fixed and erect like a pillar or monument, not liable to waste or decay, as human bodies exposed to the air are, but metamorphosed into a metallic substance, which would last perpetually. Our communion with God consists in our gracious regard to him, and his gracious regard to us. We have here therefore the communion that was between God and Abraham in the event concerning Sodom, as before in the consultation concerning It; for communion with God is to be kept up in providences as well as in ordinances.