Can illness itself become a cure?

As quoted in the first volume of ꜤUyūn al-Ḥikāyāt, a renowned shaykh in the Qādiriyyah Razawiyyah spiritual chain, Abū Qāsim Junayd Baghdādī رَحْمَةُ الـلّٰـهِ عَلَيْه said:

There was once a night I was extremely restless. I busied myself with worshipping Allah, yet I was not destined to find peace in this at that time. As much as I tried to focus on my acts of worship with khushū and khuḍū, I could not do so.

I then began reciting the Quran. Yet again, I could not focus fully for some reason, and I was not destined to receive peace from it that time. I was extremely confused as to why I could not concentrate on my worship, and why my heart was not finding the serenity it normally does from these actions.

Before morning arrived, I wrapped my shawl around my shoulders and left my home. I walked a while and came across a man also wrapped in a shawl. As I approached him, he raised his head and asked, “Why are you so worried? Has the Day of Judgement begun?”

“Has its appointed time arrived?”, I responded.  

“No”, the man explained, “I’m simply asking if you were worriedly searching for the peace your heart desires.”

I exclaimed, “Yes! I have left my home in search of peace for my heart, yet I also want to know the reason behind me feeling so restless tonight. But for now, tell me, is there anything you need?”

“Yes, there is, Abū Qāsim”, he said. “Please explain to me, is there any situation in which an illness itself becomes a cure?”