One of the virtues that Yahya ibn Adi considers is ṣidqu-l-lahja, literally righteousness of the tongue, or honesty:
It is giving information about something as it actually is. This moral quality is to be considered good as long as it does not lead to some ruinous damage.Thus one might expect that rulers would find themselves in a position where lying would be more appropriate for them. But this is not the case:
Truthfulness is to be considered good for all people, but it is best for kings and important people. As a matter of fact, lying will never suit them.So if truthfulness is best for important people, why is it so rare among them?
[Quotes from Yahya ibn Adi, The Reformation of Morals, trans. Sidney H. Griffith (Provo, Utah: Brigham Young University, 2002), 38-41.