(Imām Bukhārī narrates): Musaddad narrated the hadith to us, he said: Yahya narrated the hadith to us, from Ubaidullah, from Nafi', from Hazrat Ibn Umar (Allāh be pleased with them both), from the Prophet ﷺ, he said:

A woman should not travel without a Mahram.

Imam Ahmad has corroborated Ubaidullah, from Abdullah bin al-Mubarak, from Nafi', from Hazrat Ibn Umar (Allāh be pleased with them both), from the Prophet ﷺ.