Sayyidah Habibah bint Abi Tajra'ah (may Allah be pleased with her) said: I saw the Prophet (peace and blessings be upon him) performing the sa'i between Safa and Marwah while I was with some women of Quraysh. He (peace and blessings be upon him) was performing the sa'i behind the people, saying: "Perform the sa'i, for Allah has made the sa'i obligatory upon you." I looked at him (peace and blessings be upon him) as he (peace and blessings be upon him) was performing the sa'i, and his (peace and blessings be upon him) waist-wrapper was swirling from the intensity of the sa'i.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20945