Clarifying that Sa'i between As-safa and Al-Marwah is a pillar of Hajj, without which Hajj is not valid
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنْ عَاصِمٍ، عَنْ أَنَسٍ، قَالَ كَانَتِ الأَنْصَارُ يَكْرَهُونَ أَنْ يَطُوفُوا بَيْنَ الصَّفَا وَالْمَرْوَةِ حَتَّى نَزَلَتْ { إِنَّ الصَّفَا وَالْمَرْوَةَ مِنْ شَعَائِرِ اللَّهِ فَمَنْ حَجَّ الْبَيْتَ أَوِ اعْتَمَرَ فَلاَ جُنَاحَ عَلَيْهِ أَنْ يَطَّوَّفَ بِهِمَا}
Anas (Allah be pleased with him) reported that the Ansar felt reluctant that they should circumambulate between al-Safa' and al-Marwa until it was revealed:" Verily al-Safa' and al-Marwa are among the Signs of Allah" ; so whoever performs Hajj or 'Umra, for him there is no harm that he should circumambulate between them.