Sahih Muslim 1277
Sahih Muslim · Book 15: The Book of Pilgrimage · Clarifying that Sa'i between As-safa and Al-Marwah is a pillar of Hajj, without which Hajj is not valid
'Urwa b. Zabair narrated on the authority of 'A'isha (Allah be pleased with her) who informed him that the Ansar and the people of the tribe of Ghassan before embracing Islam pronounced Talbiya for Manat, and so they avoided circumambulating between al-Safa' and al-Marwa, and it was a common practice with their forefather, that he who put on Ihram for Manat did not circumambulate between al-Safa' and al-Marwa. And when they embraced Islam, they asked Allah's Messenger (ﷺ) about it, and then Allah, the Exalted and Majestic, revealed this verse:
وَحَدَّثَنَا حَرْمَلَةُ بْنُ يَحْيَى ، أَخْبَرَنَا ابْنُ وَهْبٍ ، أَخْبَرَنِي يُونُسُ ، عَنِ ابْنِ شِهَابٍ ، عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ ، أَنَّ عَائِشَةَ ، أَخْبَرَتْهُ أَنَّ الأَنْصَارَ كَانُوا قَبْلَ أَنْ يُسْلِمُوا هُمْ وَغَسَّانُ يُهِلُّونَ لِمَنَاةَ فَتَحَرَّجُوا أَنْ يَطُوفُوا بَيْنَ الصَّفَا وَالْمَرْوَةِ وَكَانَ ذَلِكَ سُنَّةً فِي آبَائِهِمْ مَنْ أَحْرَمَ لِمَنَاةَ لَمْ يَطُفْ بَيْنَ الصَّفَا وَالْمَرْوَةِ وَإِنَّهُمْ سَأَلُوا رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ ذَلِكَ حِينَ أَسْلَمُوا فَأَنْزَلَ اللَّهُ عَزَّ وَجَلَّ فِي ذَلِكَ { إِنَّ الصَّفَا وَالْمَرْوَةَ مِنْ شَعَائِرِ اللَّهِ فَمَنْ حَجَّ الْبَيْتَ أَوِ اعْتَمَرَ فَلاَ جُنَاحَ عَلَيْهِ أَنْ يَطَّوَّفَ بِهِمَا وَمَنْ تَطَوَّعَ خَيْرًا فَإِنَّ اللَّهَ شَاكِرٌ عَلِيمٌ}
" Verily al-Safa' and al-Marwa are among the Signs of Allah" ; so he who performs Hajj or Umra, for him there is no harm if he should circumambulate between them, and he who does good spontaneously-surely Allah is Bountiful in rewarding and Knowing.