Musnad Ahmad 25:280

Yazid narrated to us, Hajjaj informed us, from al-Hakam, from Miqsam, from Ibn Abbas, from the Prophet (peace and blessings of Allah be upon him): That he performed Tawaf of the House (the Kaaba) while on his she-camel, touching the Stone with his crooked staff, and [he did the same] between al-Safa and al-Marwa. Yazid said once: "On his mount, touching the Stone."