Narrated Ibn `Umar: Allah's Apostle said, "When the Jews greet anyone of you they say: 'Sam'Alaika (death be upon you); so you should say; 'Wa 'Alaika (and upon you).'"
Hadith ReferenceSahih Bukhari / The Book of Obliging The Apostates and The Repentance of Those Who Refuse The Truth Obstinately, and To Fight Against Such People / Hadith: 6928
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة