[A] When the Holy One, blessed be He, decided to punish the inhabitants of Sodom and to destroy the city from the face of the earth, it is written: “And Hashem said, ‘Shall I conceal from Avraham what I am doing? etc. For I have known him in order that he may command his children etc. and they shall keep the way of Hashem’” (Genesis 18:17–19). And why was it necessary to inform him? Rashi’s grandson (Rashbam) answered: “Shall I conceal from Avraham what I intend to overturn in Sodom? And I know that his children will keep the way of Hashem and will merit bringing upon them what [Hashem] spoke to Avraham—to give them the land of Canaan. And these towns are part of the inheritance of his children, as it is written in the boundary of Canaan in Parashat Noach (10:19): ‘And the border of the Canaanite was from Sidon as you come to Gerar, as far as Gaza; as you come to Sodom and Amora (Gomorrah), Admah, and Zeboiim, as far as Lasha.’ So how could I destroy his land, or the land of his neighbors, without his knowledge?”
[B] Among the Ba’alei ha-Tosafot is Rabbenu Yosef Bechor Shor, who added to the above words of Rashbam and brought support from the continuation of the verse (v. 18): “And Avraham will surely become a great and mighty nation,” etc. His words are: “That is to say, I have given this land to Avraham, and now I wish to destroy these cities that belong to him? How could I conceal it from him without his knowledge? And if you say that nothing is lost to him in this, for the land is broad enough for him and his seed? Therefore it says [that this is not so]: ‘And Avraham will surely become a great and mighty nation,’ and the entire land (is needed) [will be needed] for him. Therefore it is not for him to destroy without his knowledge. And He revealed it to him and obtained his consent, that if there are not ten righteous people there, He should destroy [the place]—and so He did. And afterward Avraham could no longer complain, for it was done according to his own words.”