Abu Dawud
The Rites of Hajj
Book Number: 004 / Hadith Number: 1899
Narated By Abdullah ibn Umar : Kathir ibn Jamhan said: A man asked Abdullah ibn Umar between as-Safa and al-Marwah: AbdurRahman, I see you walking while the people are running (between as-Safa and al-Marwah)? He replied: If I walk, I saw the Apostle of Allah (pbuh) running. I am too old.