One-fifth of Booty to the Cause of Allah (Khumus)

Bukhari :: Book 4 :: Volume 53 :: Hadith 336

Narrated 'Abdullah:

The Prophet stood up and delivered a sermon, and pointing to 'Aisha's house (i.e. eastwards), he said thrice, "Affliction (will appear from) here," and, "from where the side of the Satan's head comes out (i.e. from the East)."