Rashi on Genesis 18:32/רש"י על בראשית י״ח:ל״ב

1אולי ימצאון שם עשרה PERADVENTURE THERE SHALL TEN BE FOUND THERE — For a smaller number he did not plead because he knew already of two instances where less than ten had failed to save the wicked. He said to himself: In the generation of the Flood there were eight righteous people, viz., Noah, his sons and their wives, and they could not save their generation (Genesis Rabbah 49:13), and for nine in association with God he had already pleaded but had found no acceptance.