Sahih Muslim | Book 43 | Hadith Number 7176

Narrated by Ibn Abbas
Ibn Abbas reported that some Muslims met a person with a small flock of sheep. He said:

As-Salam-o-'Alaikum. They caught hold of him and killed him and took possession of his flock. Then this verse was revealed: "He who meets you and extends you salutations, don't say: You are not a Muslim" (iv. 94). Ibn 'Abbas, however, recited the word as- Salam instead of "as-Salam".