The Messenger of Allah ﷺ said, "When any of you comes to a gathering, let him give the greeting of peace. If he then wishes to sit, let him do so, and when he gets up to leave, let him give the greeting of peace again. The first is no more obligatory than the second."
حدثنا قران بن تمام عن محمد بن عجلان عن سعيد بن أبي سعيد
قال رسول الله ﷺ إذا أتى أحدكم المجلس فليسلم فإن بدا له أن يقعد فليسلم إذا قام فليست الأولى بأوجب من الآخرة
Its chain of transmission is sahih. Qaran bin Tammam Asadi, his reliability was already established at 4956, and we add here that Ibn Saad mentioned him in his biographical entry at 6:278, 7/2/84, as did Ibn Abu Hatim at 3/2/144. The hadith is a repetition of 7142, and we have already noted this there.