All the stories
Chapter 1: On the conduct of kings

The expedient lie

I heard of a king who gave the order for a prisoner to be killed. The wretch, in that state of hopelessness, began to abuse the king and revile him — for it is said that whoever washes his hands of life says whatever is in his heart.

The king asked, "What is he saying?" One of the well-natured viziers replied, "My lord, he is saying: 'and those who restrain their anger and pardon people.'" The king was moved to mercy and spared his blood.

Another vizier, who opposed the first, said, "Men of our sort should speak nothing but the truth before kings. He was abusing you and cursing you." The king's face darkened at this and he said, "That lie of his pleased me better than this truth of yours — for that one faced toward a good end, and this one was built on malice."

دروغی مصلحت‌آمیز به که راستیِ فتنه‌انگیز

هر که شاه آن کند که او گوید حیف باشد که جز نکو گوید

An expedient lie is better than a truth that stirs strife. If a king does what his adviser says, it is a shame for that adviser to say anything but good.

Source: گلستان، تصحیح فروغی