From his location outside the city of Hebron, Abram could look down over the Dead Sea and south toward Sodom and Gomorrah. The day before Abram had stood here looking over this same city and its land with the three heavenly visitors (the Lord and two angels, Genesis 18:16-33). The site of the explosive destruction still smoldered into the following morning.
God had destroyed Sodom and Gomorrah, but not without first rescuing Lot because the text says, God "remembered Abraham." The word "remember" is the Hebrew word zakar which is used in regard to a covenant. God "remembers" to be loyal and faithful to his covenant. God had "remembered" Noah during the Flood because he had given Noah a promise (Genesis 8:1) and "God remembered Rachel" in Genesis 30:22. This same word will be used in Exodus when God comes to the rescue of his people in Egypt. To "remember" means God is acting to fulfill the promise or covenant he had made:
"God heard their groaning and he remembered (zakar) his covenant with Abraham, with Isaac and with Jacob." - Exodus 2:24 (and, Exodus 6:5; 32:13; Lev. 26:42-45; Psalm 105:42; 106:45)
God remembered his covenant with Abraham when God rescued Lot from the city before he destroyed it. God honored his covenant with Abraham by delivering Lot, and then the Lord sent "the catastrophe that overthrew the cities where Lot had lived."
The point here is that Abraham had saved Lot just like a remnant of righteous people could have spared Sodom. Since that remnant did not exist there was no hope for that city. But, because of God's covenant with Abraham, there was hope for Lot. And, since there was hope for Lot there would be hope for the two nations that would come from him: Moab and Ammon.
It is interesting to mention that Jeremiah ends both of his prophecies about Nebuchadnezzar's destruction of Moab and Ammon (spoken by Jeremiah in 603 BC and fulfilled in 582 BC) with words of a promised restoration. Could it be that the same covenant Abraham had with God that spared Lot from Sodom will, in the future, restore Moab and Ammon?
" 'Yet I will restore the fortunes of Moab in days to come,' declares the Lord" - Jeremiah 48:47
" 'Yet afterward, I will restore the fortunes of the Ammonites,' declares the Lord." - Jeremiah 49:6