Oaths and Vows (Kitab Al-Aiman Wa Al-Nudhur)
Dawud :: Book 21 : Hadith 3297
Narrated Abdullah ibn Abbas:
The sister of Uqbah ibn Amir took a vow that she would perform hajj on foot, and she was unable to do so. The Prophet (peace_be_upon_him) said: Allah is not in need of the walking of your sister. She must ride and offer a sacrificial camel.