Sahih al-Bukhari 3684
In-book no 3684وَقَالَ ابْنُ وَهْبٍ أَخْبَرَنَا عَمْرٌو، عَنْ بُكَيْرِ بْنِ الأَشَجِّ، أَنَّ كُرَيْبًا، مَوْلَى ابْنِ عَبَّاسٍ حَدَّثَهُ أَنَّ ابْنَ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ لَيْسَ السَّعْىُ بِبَطْنِ الْوَادِي بَيْنَ الصَّفَا وَالْمَرْوَةِ سُنَّةً، إِنَّمَا كَانَ أَهْلُ الْجَاهِلِيَّةِ يَسْعَوْنَهَا وَيَقُولُونَ لاَ نُجِيزُ الْبَطْحَاءَ إِلاَّ شَدًّا
Narrated Ibn 'Abbas: To run along the valley between two green pillars of Safa and Marwa (mountains) was not Sunna, but the people in the pre-islamic period of ignorance used to run along it, and used to say: "We do not cross this rain stream except running strongly. "