Analysis:
This quatrain by Saadi Shirazi is a profound exploration of human suffering, particularly the emotional pain caused by betrayal and loss of friendship.

Physical and Emotional Pain: The initial images of a needle in the eye and a burning haystack represent physical pain, but they also symbolize the intense emotional pain of betrayal.
Isolation and Confinement: The image of a chain around the neck in a foreign land signifies isolation, confinement, and a sense of being trapped.
The Worst Pain: The final line suggests that the greatest pain is not physical or situational, but emotional. The loss of a friend and the presence of an enemy is the ultimate betrayal.

Themes:

Betrayal: The central theme is the pain of betrayal and the loss of friendship.
Suffering: The quatrain explores different forms of suffering, both physical and emotional.
Isolation: The image of being chained in a foreign land highlights the theme of isolation.
The value of friendship: The final line emphasizes the importance of friendship and the pain of losing it.

Deeper Meaning:

This quatrain suggests that while physical pain and external circumstances can be difficult to endure, the emotional pain caused by betrayal is perhaps the most profound. The speaker is willing to endure physical suffering and isolation rather than face the betrayal of a friend. This highlights the deep-seated human need for connection and belonging.

This quatrain is a powerful reminder of the fragility of human relationships and the enduring pain of betrayal. It invites us to reflect on the importance of friendship and the devastating consequences of losing it.