Nasrudin didn't part with his ring because he was attached to it, which the story clearly identifies as "an ordinary vice." Though as a teacher, Nasrudin may have taught his student a valuable lesson in non-attachment, Nasrudin himself was caught up in materialist attachment. This demonstrates two things: (1) we often know the best answers but fail to heed them ourselves; (2) we can be a positive influence for others even when we ourselves are less than perfect in our own adherence to the truths we that we espouse.
On Aug 1, 2023 Brian B wrote :