John Calvin Commentary Genesis 19:27

"And Abraham gat up early in the morning to the place where he had stood before Jehovah:" — Genesis 19:27 (ASV)

And Abraham got up early in the morning. Moses now reverts to Abraham and shows that he, by no means, neglected what he had heard from the mouth of the angel; for he relates that Abraham came to a place where he could see the judgment of God. For we must not suspect that (as we have recently said concerning Lot’s wife) he trusted more to his own eyes than to the word of God, and that he came to explore because he was in doubt.

But we rather infer from the text that, already persuaded that the angel had not spoken in vain, he sought confirmation by actually seeing the event, a confirmation that would be useful both to himself and to posterity. And it is not to be doubted that during the whole night, he suffered severe anguish concerning the safety of his nephew Lot.

Whether he became satisfied on this point or not, we do not know; yet I rather incline to the conjecture that he remained anxious about him. And it is possible that, hesitating between hope and fear, he went forward to meet him, so that he could see whether he was delivered or not.

And although he beholds nothing but the smoke, which generally remains after a great fire, yet this sign is given to him from the Lord, as a testimony to posterity, of a punishment so memorable.

God indeed designs that a monument of His wrath should exist forever in the very appearance of the place. However, because the world is so ready to doubt God’s judgments, and it could easily have been believed that the place had always been this way, or that the change had occurred accidentally, the Lord was pleased to show His act of vengeance before Abraham’s eyes, so that he might serve as a herald to posterity.