Musnad Ahmad 1153:455

Muhammad ibn Bakr narrated to us, he said: Ubayd Allah ibn Abi Ziyad informed us, he said: Al-Qasim ibn Muhammad narrated to us, from Aisha, she said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "The circumambulation (Tawaf) of the Kaaba, the walking between As-Safa and Al-Marwa, and the stoning of the pillars (Jamarat) were only ordained for the establishment of the remembrance of Allah, the Almighty and Majestic."