Nafi' narrates that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) used to have a freed slave-woman of his, called Safiyyah, ride behind him, and she would travel with him to Makkah.
(b) In the narration of Uqbah: Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) performed Hajj with a freed slave-woman of his, called Safiyah, (riding) on the rear of a camel.
Imam al-Shafi'i (may Allah have mercy on him) said in his new opinion: It has reached us from Aishah, Ibn Umar and Urwah the like of our view that a woman may travel for Hajj even if no mahram is with her. He also mentioned it from Ata, and, in his old opinion, from Malik bin Anas.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10132