Musnad Ahmad 1153:1062

Waki’ narrated to us, from Sufyan, from ‘Ubayd Allah ibn Abi Ziyad, from al-Qasim, from ‘Aishah, she said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The circumambulation (Tawaf), the striving (Sa’i) between al-Safa and al-Marwah, and the stoning of the pillars (Ramy al-Jimar) were only ordained for the establishment of the remembrance of Allah, the Almighty and Majestic."