Abu Dawud Book 4, Hadith Number 1899.
Chapter : Not known.
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.