Musnad Ahmad 482:95

'Abd al-Razzaq and Ibn Bakr narrated to us, they said: Ibn Jurayj informed us, Sa'id ibn Abi Ayyub informed me, that Yazid ibn Abi Habib informed him, that Abu al-Khayr narrated to him, from 'Uqbah ibn 'Amir al-Juhani, that he said: My sister vowed to walk to the House of Allah, the Almighty and Majestic. She ordered me to ask the Messenger of Allah, peace and blessings of Allah be upon him, for a religious ruling on her behalf. So I asked the Prophet, peace and blessings of Allah be upon him, for a ruling, and he said: "Let her walk and let her ride." He said: "And Abu al-Khayr would not depart from 'Uqbah."