The Lord shares with Abraham what is going to be done to Sodom and Gomorrah. Instead of saying something like, "Well, that's the will of God," Abraham expressed dissent.
We are told "Abraham remained standing before the Lord." And he didn't stand there silently. He began arguing, bargaining. "Suppose there were fifty righteous men in the city; would you destroy them too?" Rather than engage in bargaining by offering a higher number, the Lord agree that fifty would be enough to save the city. Abraham countered by saying forty-five, then forty, thirty, twenty, ten.
Abraham keeps arguing justice; the Lord keeps demonstrating mercy (I've been reading the Wesley Study Bible).
The lectionary has paired this passage with the lesson from Luke about prayer. Jesus told his disciples to be persistent, to ask and to search. He reminded them what Abraham would have already known that we are to continue standing before the Lord, to continue to ask the Lord for care.
(Note: although we are accustomed to assuming the sin of Sodom was homosexuality, Bible scholars point out to us that the text actually presents inhospitality as what they were doing that deserved punishment.)