What does Macbeth hear a voice saying?

In William Shakespeare's play The Tragedy of Macbeth, thought to be first performed in the year 1606, Macbeth hears a voice saying that he murdered sleep. The title character Macbeth was a Scottish general who met three witches; they prophesied that one day he would become King of Scotland.

The thought of power drives Macbeth, encouraged by his wife Lady Macbeth, to murder King Duncan and become King himself. Macbeth's announcement about murdering sleep is mirrored by Lady Macbeth's sleepwalking. This play is known as a tragedy, and is often thought by actors to be cursed, and who therefore refer to it as "The Scottish Play."