The Bustān of Sadi Translated from the Persian with an...

In relation to an absent friend, two things are unlawful. The first is to squander his possessions; the second, to speak evil of his name.

Look not for good words from him who mentions the names of men with scorn, for behind thy back he says those things which he said to thee of others.

He only is wise who concerns himself with his own affairs and is indifferent to the world.