Flute of Sheep

The Flute of Sheep is an artifact found only in the NES port of  Ultima IV.

Description
One of the many nameless skeletons that roam the ruins of Magincia can tell the Stranger in this version of the game that the town hides a treasure, and that its inhabitants no longer have need of it. Seeking amidst the battered buildings of the dead city, the hero may find this relic in a chest within a hidden passage beneath ground.

Usable only by characters of the Shepherd class, the flute's melody has a random chance of driving all of the enemies who hear it into an enchanted slumber, similar to what might be achieved by the Sleep or Mass Sleep spells.