Chapter 32: Dialects and Readings of the Qur'an (Kitab Al-Huruf Wa Al-Qira'at)
Narrated Ibn 'Abbas: The Muslims met a man with some sheep of his. He said: Peace be upon you. But they killed him and took those few sheep. Thereupon the following Qur' anic verse was revealed: "... And say to anyone who offers you a salutation: Thou art none of believer, coveting the perishable good of this life." meaning these few sheep.
Sunan Abi Dawud 3974