Human beings are members of a whole,
In creation of one essence and soul.
If one member is afflicted with pain,
Other members uneasy will remain.
If you’ve no sympathy for human pain,
The name of human you cannot retain!
According to Wikipedia (although not really a great academic source):
Abū-Muḥammad Muṣliḥ al-Dīn bin Abdallāh Shīrāzī (Persian: ابومحمد مصلح الدین بن عبدالله شیرازی) better known by his pen-name as Saʿdī (Persian: سعدی) or, simply, Saadi, was one of the major Persian poets of the medieval period. He is not only famous in Persian-speaking countries, but he has also been quoted in western sources. He is recognized for the quality of his writings, and for the depth of his social and moral thoughts.