Helping others preserve their dignity is a key part of service. Dingity is a good trait to have.A good example is the loyalty to mothers.
If you're referring to the one who quote that sentence, it would be unknown, but it is a really famous quote.
If
you wanted to restates the main idea of this quotation , it would be :
it's not good to criticize others because we don't know that they face
in life.
hope this helps!