Musnad Abu Ya'la al-Mawsili 110:12

Narrated to us Muhriz ibn ‘Awn, narrated to us Sufyan, from ‘Amr, from ‘Ata’, from Ibn ‘Abbas, who said: The Prophet, may Allah bless him and grant him peace, only performed *sa‘y* (brisk walking) in the House (the Ka‘bah) and between al-Safa and al-Marwah to show the people his strength.