One of Saadi’s most well-known poetry is this one where he considers all humans as different parts of a whole body.
The poem comes from Saadi’s book: the Gulistan.
Human beings are members of a whole,
In the creation of one essence and soul.
If one member is afflicted with pain,
Other members uneasy will remain.
If you have no sympathy for human pain,
The name of a human you cannot retain.