Sayyiduna Mu’adh bin Anas al-Juhani (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him) said: Whoever comes to a gathering, it is his duty to say salam, and whoever stands up to leave a gathering, it is also his duty to say salam when leaving. Meanwhile, a man stood up to leave, and since the Noble Prophet (peace and blessings be upon him) was still engaged in conversation, he left without saying salam. The Prophet (peace and blessings be upon him) said about him: He has forgotten the matter very quickly.
Hadith Referenceالفتح الربانی / كتاب السلام والاستئذان وآداب أخرى / 8267
Hadith Gradingمحدثین:ضعیف
Hadith Takhrij«اسناده ضعيف لضعف زبان بن فائد وسھل بن معاذ في رواية زبان عنه، أخرجه الطبراني في الكبير : 20/ 408 ، (انظر مسند أحمد ترقيم الرسالة: 15615 ترقیم بيت الأفكار الدولية: 15700»
Brief Explanation
Benefits: … The first greeting of peace (salam) is that which is given upon entering a gathering, and the second is that which is given upon leaving the gathering. Both greetings of peace are necessary; the importance of one is not greater than the other, nor does one have superiority over the other. Rather, both are necessary.