What is the significance of Hajj-at-Tamattu` according to Prophet Muhammad (saw)?
 Narrated Sa`id bin Al-Musaiyab:                     `Ali and `Uthman differed regarding Hajj-at-Tamattu` while they were at 'Usfan (a familiar place near Mecca). `Ali said, "I see you want to forbid people to do a thing that the Prophet did?" When `Ali saw that, he assumed Ihram for both Hajj and `Umra.