Hisham bin 'Urwa هشام بن عروة · Chapters on Seeking Permission

that the Messenger of Allah (ﷺ) said: "When one of you arrives at the gathering, then give the Salam, and if he is given a place to sit, then let him sit. Then when he stands, let him give the Salam, the first is more worthy than the last."

that the Messenger of Allah (ﷺ) said: "No two Muslims meet each other and shake hands, except that Allah forgives them before they part."