Question: What can be considered the greatest punishment in spirituality?

Answer: It is when a person loses the desire for spirituality.

Question: All corporeal punishments come from the Creator. What can be considered the greatest corporeal punishment?

Answer: The one that prevents a person from engaging in spiritual advancement.
[329461]
From the Daily Kabbalah Lesson 5/13/24, Writings of Rabash “Knowledge and Faith”

Related Material:
Spiritual Punishment
If You Leave Me For A Day…
For What Actions Does the Creator Punish a Person?