The Cave of Machpelah ("Tomb of the Patriarchs"), where our Patriarchs and Matriarchs Abraham and Sarah, Isaac and Rebecca, Jacob and Leah are buried, is the piece of property whose purchase is recorded in Genesis 23:1-20. Abraham bought the cave and the surrounding field from Ephron the Hittite as a burial place for his wife Sarah.
The four holiest cities in Israel are Jerusalem, Hebron, Tzfat and Tiberias. Each corresponds to an element - Jerusalem to fire, Hebron to earth, Tzfat to air and Tiberias to water.
In keeping with the earth element theme - Hebron is HEAVY.
Prayers at the Tomb of the Patriarchs and Matriarchs are heavy, and yet, defying gravity itself, they ascend upward at surprising speed.