The merchant of Baghdad

There was once a merchant in the famous market at Baghdad.

One day he saw a stranger looking at him in surprise. And he knew that the stranger was Death. Pale and trembling, the merchant fled the marketplace and made his way many many miles, to the city of Samarra. For there he was sure Death could not find him. But when, at last, he came to Samarra, the merchant saw, waiting for him, the grim figure of Death..

“Very well ” said the merchant. “I give in. I'm yours”

”But tell me why did you look surprised when you saw me this morning in Baghdad?”

“Because”, said Death. “I had an appointment with you tonight. In Samarra”

Source: intro of ep2 season4 Sherlock