Sahih Muslim Book 7, Hadith Number 2924.

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

Hisham b. ‘Urwa narrated on the authority of his father who reported: I said to ‘Aisha: I do not see any harm to me if I do not circumambulate between al-Safa’ and al-Marwa. She said: On what ground do you say so? (I said:) Since Allah, the Exalted and Majestic, says: “Verily al-Safa’ and al-Marwa are among the Signs of Allah.” It (your assertion) were (correct), it would have been said like this: “There is no harm for him, that he should not circumambulate between them.” It (this verse) has been revealed about the people of Ansar. Whenever they pronounced the Talbiya, they pronounced it in the name of al-Manat during the Days of Ignorance; so they (thought) that it was not permissible for them (for the Muslims) to circumambulate between and al-Marwa. When they (the Muslims) came with Allah’s Apostle (may peace he upon him) for Hajj, they mentioned it to him. So Allah, the Exalted and Majestic, revealed this verse. By my life, Allah will not complete the Hajj of one who has not circumambulated between al-Safa and al-Marwa.