"We already find in Ezekiel a part of Sheol distinguished as deeper, called the "pit" or "the lowest parts of the earth", where the uncircumcised descend and those who have fallen by the sword, causing terror in the land of the living. In course of time this distinction came to be more definite: the upper part of Sheol, destined for the just, was called "Abraham's bosom", and the lower part became Gehenna, where sinners were tormented in flames."
January 1, 1970
https://en.wikiquote.org/wiki/Gehinnom