Abu-al-Faraj Ibn Harun (Gregory Bar hebraeus). The book is entertaining stories (№ 221431)

Once the ruler of Anushirvan issued an order banning there are those meals that he eats, and drink the drinks that he drinks. Shortly thereafter, one high-ranking dignitary prepared a Royal dish, and invited another officer to share his meal. A dinner, a guest wrote Anushirvan a denunciation of the owner, treats his forbidden dish. "I saw it and not in forces to hide from you," he wrote.
In response, the informer received from Anushirvan the following message written on the reverse of the accusation*:
"We give you praise for loyalty and strongly condemn the violator of the order. Especially for the fact that he can't keep secrets and reveals them to such as you."