Abraham goes six rounds with God

In Genesis 18 the Lord visits Abraham and Sarah to announce that they will have a child within a year and also let Abraham know that the sin of Sodom and Gomorrah had reached a level that God had come down to 'see for himself'. Obviously God knew what was happening but He purposefully orchestrated a discussion with Abraham that prompted Abraham to plead for the lives of the righteous who lived in Sodom and Gomorrah. 

In verse 17 the Lord quizzically asks "shall I hide from Abraham what I am going to do since he's getting all the blessing anyhow and why should it matter to him?" (paraphrased). Of course God is inviting a response, and pleasingly, when Abraham hears God's question he doesn't blithely wander back home content in the knowledge that God had promised him great things, but rather he comes before the Lord and and asks:

“Would You also destroy the righteous with the wicked? 24 Suppose there were fifty righteous within the city; would You also destroy the place and not spare it for the fifty righteous that were in it? 25 Far be it from You to do such a thing as this, to slay the righteous with the wicked, so that the righteous should be as the wicked; far be it from You! Shall not the Judge of all the earth do right?”

As we know, God says He wouldn't (and He wouldn't) and Abraham in various states of anxiety  repeatedly asks God if He would destroy them if there 45, 40, 30, 20 and finally ten righteous people in the city?

Why Abraham asked and asked until he was down to ten righteous could possibly be the fact that his nephew Lot was living in Sodom and married with children and I'm guessing he was estimating Lot's family numbered at least ten people. Abraham would have remembered that Lot had been a wealthy livestock owner when he and Abraham had parted ways years earlier so there was possibility that Lot's extended family would even be larger.

During this discussion Abraham is very aware that he is talking to God and he is obviously extremely uncomfortable speaking to God this way and refers to himself as "dust and ashes" and asks the Lord not to be angry with him. Somehow I think God would be rejoicing at Abraham's concern not only for Lot but also that His name should be without reproach.
The chapter then ends with "So the Lord went His way as soon as He had finished speaking with Abraham; and Abraham returned to his place."

This is a typically succinct Genesis statement and it is my guess is that Abraham returned to his tent to continue to intercede for his nephew as later verses intimate. 

The destruction of Sodom and Gomorrah and the divine rescue of Lot the next day follows in chapter 19 and it gives some further insight into Abraham's concern for Lot:

27 And Abraham went early in the morning to the place where he had stood before the Lord. 28 Then he looked toward Sodom and Gomorrah, and toward all the land of the plain; and he saw, and behold, the smoke of the land which went up like the smoke of a furnace. 29 And it came to pass, when God destroyed the cities of the plain, that God remembered Abraham, and sent Lot out of the midst of the overthrow, when He overthrew the cities in which Lot had dwelt.

Abraham was up early next morning and probably anxiously went back to the place he interceded before the Lord. Abraham would not have known what happened to Lot but he would be well aware that there were less than ten righteous people in Sodom. Further I'm sure that Abraham was confident in God's character but he may have been less sure of Lot's! 

In verse 29b in italics above we see that God had responded to Abraham's intercession with specific reference to Lot being rescued because of Abraham's intercession.

We know Lot fled to Zoar and then into the hills but strangely at no time does Lot consider turning to his uncle for help. Obviously Lot's later story becomes known but how long after the cataclysm we have no idea. It is also interesting to consider the next chapter in which we see Abraham suddenly moving from Hebron to Gerar. No explanation is given but I wonder if it was because of the acrid smoke from the fires that may have continued for months as the area was full of sulphur pits and asphalt, or even more importantly, Abraham's grief at the supposed death of his nephew and his family.