God is not a man, that He should lie, nor a son of man, that He should change His mind; has He said and will not do, or spoken and will not fulfill it?
Torah Temimah: Pesachim 111a — practical ruling drawn from the phrasing of this verse regarding pairs.
English: Our Rabbis taught: Three [things] one does not pass between, and one is not passed between — a dog, a palm tree, and a woman; and some say also a pig; and some say also a snake. And if one did pass between, what is the remedy? Rav Pappa said: Begin with El and conclude with El; or begin with lo and conclude with lo.
Halakhic-protective practice anchored to the verse’s wording (אל / לא).
The doubled divine negation in the verse becomes a formula of protection — the same words that declare God’s reliability shield the traveler.