(474) بَابُ كَيْفَ رَدُّ السَّلامِ؟
Mu'awiya ibn Qurra said that his father said to him, "My son,when a man passes by you and says, 'Peace be upon you (plural).' Do notsay, 'And on you (singular)' as if you were singling out that greetingout for him alone. Rather say, 'Peace be upon you (plural).'"
Reference: Al-Adab Al-Mufrad 1037
In-book reference: Book 42, Hadith 74
English translation: Book 42, Hadith 1037