Beha'alot'cha: Chapter 14
"Everything that comes into the fire... you shall pass through the fire"

We learn that the soul is the vessel of God, and that God will not dwell in it until it is purged in the fire of Gvurah. Also, people are cleansed by the Written Torah from the right, that is referred to as 'water.' The completely wicked are purified in Gehenom but those who study the Oral Torah and the Written Torah are purified through the Torah.