Sayyiduna Abu Sa'id (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "No woman should travel a journey of three days or more unless her father, her brother, her son or a mahram of hers is with her."
(b) Qaza'ah bin Yahya narrates it from Sayyiduna Abu Sa'id (may Allah be pleased with him); in one of the two narrations from him he says: "More than three," and in the other: "Two days."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10137