Shaking Hands When Entering Upon Those Who Are Sitting
Is there proof from the Book or the Sunnah or action of the Prophet (peace and blessing upon him) for shaking hands when one enters upon those that are sitting? May Allah reward you with good.
I don’t know anything of this kind from the Sunnah, for this reason it is not appropriate for you to do so. Some people when they enter a gathering they begin with the handshake from the first person to the last person and this is not legislated from what I know, and shaking hands is only for when meeting one another, as for when entering the gathering, then it is not from the manhaj of the Messenger (peace and blessing upon him or his companions) that they would do that. The Messenger (peace and blessing upon him would come and sit at the end of the majlis (sitting room) and we never heard also that if he sat at the end of the majlis that they would stand up and shake his hand, so shaking hands in this manner is not legislated. I asked about this to those who we rely upon from our Shaykhs, so they said we do not know for this an origin in the sunnah…
Shaykh Muhammad bin Saalih al-`Uthaymeen
Bid’ah wa Muhdathaat wa ma la Asla lahaa Pg: 478
Translated by Muhammad Elmi.