When man follows God’s instructions and lives a moral life, the earth works in harmony with man. Put another way, when man (אדם) is God’s footstool (הדום) the earth (אדמה) is man’s footstool.
Now that Kayin has done such a terrible crime, even though his calling was to work the earth, he will not succeed at that. The ground will not respond favorably to his efforts. He is נע, constantly moving. He can’t find a place to call his own.
He is also נד, isolated from society.
This is a harsher punishment than death. Indeed God declares his continuing to live to be seven-fold worse than death. His difficult existence will serve as a warning to anyone considering murder.
Beraishis 4:11-15
pages 134-139
