Jami` at-Tirmidhi 2966

Narrated 'Asim Al-Ahwal:"I asked Anas bin Malik about As-Safa and Al-Marwah, and he said: 'They were among the rites of Jahiliyyah.' He said: 'So during Islam, we refrained from them, then Allah, Blessed and Most High, revealed: Indeed As-Safa and Al-Marwah are of the symbols of Allah. So it is not a sin for those who perform Hajj or 'Umrah to the house to go between them. (2:158)' He said: 'So it is voluntarily then verily, Allah is the All-Recogniser, the All-Knowing. (2:)