Sforno on Numbers 16:32/ספורנו על במדבר ט״ז:ל״ב

1ותפתח הארץ את פיה, the fissure in the surface of the earth became wide enough to extend all the way to their houses.

2כל האדם אשר לקרח, all the people who had made common cause with Korach in this rebellion. Seeing that this is the meaning of the these words, we need not be surprised to be told that Korach’s sons did not die, as they did not “belong” to their father spiritually or philosophically.

3ואת כל הרכוש, this was so that his righteous sons not be burdened with inheriting the ill gotten gains of their father. [the author quotes a Sifri on Ki Teytze item 283 in support of this. Ed.]