My sister took a vow to walk on foot to the House of Allah (i.e. Ka'bah). She asked me to consult the Prophet ﷺ about her. So I consulted the Prophet ﷺ. He said: Let her walk and ride. (Using translation from Abū Dāʾūd 3299)  

أَنْ أَسْتَفْتِيَ لَهَا رَسُولَ اللهِ ﷺ فَاسْتَفْتَيْتُ النَّبِيَّ ﷺ فَقَالَ «لِتَمْشِي وَلْتَرْكَبْ»