Sayyiduna Uqbah bin Amir al-Juhani (may Allah be pleased with him) said: His sister made a vow that she would go for Hajj on foot and with her head uncovered. I mentioned this to the Prophet (peace and blessings of Allah be upon him), so he said: "Tell your sister to cover her head and ride, and to fast for three days." (i.e., to give expiation for not fulfilling the vow).