50, 45, 40, 30, 20, 10… What is this, an auction? What exactly is Avraham trying to do in this rather bizarre exchange with Hashem? Rabbeinu Bechayai points out that within this dialogue between Avraham and Hashem, Avraham tells Hashem twice that it would be a pity to destroy Sodom. R. Bechayai says that the two statements of pity in which Avraham is imploring Hashem to save the city parallel two of the attributes of Hashem, mercy and judgment. Avraham is saying to Hashem that even from judgment they deserved to be spared and all the more so, in all of Your great mercy they should be spared. R. Bechayai continues by saying that throughout this section of the Torah, even though it may not be apparent to us, Hashem really is dealing with Sodom and Gomorrah with mercy, as it is stated (Genesis 18:20), "Sodom and Gomorrah cried out greatly and have sinned heavily" as well as, "If I find in Sodom fifty righteous people within the city, I will spare the entire city (18:26)." But, as R. Bechayai points out, men cannot understand the accounting of Hashem. The destruction of Sodom was ultimately coming from the highest place of mercy, as Hashem heard their cry and would have spared the city but realized that the only way they could truly be saved was through their destruction.
This type of display of Hashem's mercy is also seen at the Song at the Sea. "Your right hand, Hashem, is adorned with strength; Your right hand, Hashem, smashes the enemy (Exodus Ch.14)." Rashi explains that even when Hashem is destroying his enemies, He does it with His right hand, the hand of kindness, love, and mercy.
It says in Tractate Rosh Hashana that Hashem will display the 13 character traits of mercy upon us when we ourselves display these traits upon each other first. It seems to me that we must work hard everyday to make sure that we are treating each other in such a way. But we must look even deeper than we realize in order to begin truly treating each other with real mercy. As we see in Hashem's dealings with Sodom and the Egyptians, sometimes mercy must come in ways that may seem harsh to others. Of course, for Hashem there is no difficulty in being able to maintain the intention of mercy within an act that may seem harsh to others. However, with us, this is not so easy. We often treat people very harshly. But this is usually coming from a place of anger and lack of understanding. The next time we think it necessary to deal with another person in a strong way, we must remember that Hashem wants us to treat each other with mercy and that that may mean being strong, but to be very clear that it is truly out of love and respect for the other and in hopes of their growth that we are behaving the way we do. If you can't do it with love and understanding, maybe you shouldn't do it at all.