Bashr bin Hilal al-Swaf بشر بن هلال الصواف · The Book on Hajj

"I saw Ibn Umar walking at the place of Sa'i so I said to him: 'Do you walk at the place of Sa'i between As-Safa and Al-Marwah?' He said: 'If I performed Sa'i, then it is because I saw the Messenger of Allah performing Sa'i there, and if I walked, then it is because I have seen the Messenger of Allah walking. And I am an old man.'"