(450) بَابُ فَضْلِ السَّلامِ
Abu Hurayra reported that a man passed by the Messenger of Allah,may Allah bless him and grant him peace, while hew as in an assembly andsaid, "Peace be upon you." "Ten good deeds," he said. Another man passedby and said, "Peace be upon you and the mercy of Allah." The Prophet said,"Twenty good deeds." Then yet another man passed by and said, "Peace beupon you and the mercy of Allah and His blessing," and the Prophet said,"Thirty good deeds." Then a man in the gathering got up and did not givethe greeting. The Messenger of Allah, may Allah bless him and grant himpeace, said, "How quickly your companion forgets! When one of you comesto an assembly, he should give the greeting. If he thinks he should sitdown, he sits down. When he stands up, he gives the greeting. Neither isa greater duty than the other."
Reference: Al-Adab Al-Mufrad 986
In-book reference: Book 42, Hadith 22
English translation: Book 42, Hadith 986