Sahih Muslim Book 7, Hadith Number 2921.

Chapter : It is permissible to observe Tawaf on the back of a camel or any other riding beast, and to touch the black stone with a stick.

Abu Tufail reported: I saw Allah’s Messenger (may peace be upon him) circumambulating the House and touching the corner with a stick that he had with him, and then kissing the stick.