Sahih Muslim Book 26, Hadith 13
What is the matter with him? They said: He had taken the vow to walk (on foot to the Ka'ba). Thereupon he (Allah's Apoitle) said: Allah is indifferent to his inflicting upon himself chastisement, and he commanded him to ride.
This hadith is narrated on the authority of Ayyub with the same chain of transmitters and a slight variation of words.
Allah's Apostle (ﷺ) found an old man walking between his two sons supported by them, whereupon Allah's Apostle (ﷺ) said: What is the matter with him? He (the narrator) said: Allah's Messenger, they are his sons and there is upon him the (fulfilment) of the vow, whereupon Allah's Apostle (ﷺ) said: Ride, old man, for Allah is not in need of you and your vow.