(Imām Bukhārī narrates): Ishaq bin Ibrahim al-Hanzali narrated the hadith to us, he narrated: I said to Abu Usamah: Ubaidullah narrated the hadith to you, from Nafi', from Hazrat Ibn Umar (Allāh be pleased with them both), that the Prophet ﷺ said that

a woman should not undertake a journey of three days without a Mahram.