Sahih Muslim Book 7, Hadith Number 2925.

Chapter : Sa’i between al-Safi’ and at-Marwi is essential rite of Hajj and Hajj is not complete without it.

‘Urwa b. Zabair reported: I said to ‘Aisha, the wife of Allah’s Apostle (may peace be upon him): I do not see any (fault) in one who does not circumambulate between al-Safa’ and al-Marwa, and I do not mind if I do not circumambulate between them, whereupon she said: O, the son of my sister, what you say is wrong. Allah’s Messenger (may peace be upon him) observed Sa’i and so did the Muslims. So it is a Sunnah (of the Prophet). And it was a common practice (with the pagan Arabs) that those who pronounced Talbiya for the wretched al-Manat, situated at Mushalla, did not observe Sa’i between al-Safa’ and al-Marwa. With the advent of Islam, we asked Allah’s Apostle (may peace be upon him) about this practice, and (it was on this occasion) that Allah, the Exalted and Majestic, revealed this verse: “Verily al-Safa’ and al-Marwa are among the Signs of Allah”; so he who performed Hajj or ‘Umra it is no sin on him if he circumambulates them. And if it were as you state, (then the wording would have been): “There is no harm for him, that he should not circumambulate round them.” Zuhri said: I made a mention of that to Abu Bakr b. ‘Abd al-Rahman b. al-Harith b. Hisham; he was impressed by that and said: This is what is called knowledge. And I have heard many a scholar saying: Many of the Arabs who did not circumambulate between al-Safa’ and al-Marwa said: Our circumambulation between these two hills is an act of ignorance; whereas others among the Ansar said: We have been commanded to circumambulate the House, and not Commanded to run between al-Safa’ and al-Marwa. So Allah, the Exalted and Majestic, revealed this verse: “Verily al-Safa’ and al-Marwa are among the Signs of Allah.” Abu Bakr b. ‘Abd al-Rahman said: I think that this (verse) has been revealed for such and such (persons).