Abu al-Khayr narrates from Sayyiduna Uqbah bin Amir (may Allah be pleased with him): My sister vowed that she would walk barefoot to the House of Allah, and she said to me: "Ask the Prophet (peace and blessings be upon him)." I asked him (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Let her walk, and let her also ride."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النذور / 20113