The Book of Pilgrimage (Kitab Al-Hajj)
Muslim :: Book 7 : Hadith 3097
This hadith has been narrated on the same authority by Ubaidullah. And in the narration of Abu Bakr (the words are):" More than three (days)." Ibn Numair narrated on the authority of his father, (and the words are):" Three (days) except (when) she has a Mahram with her."