أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا حُمَيْدٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، قَالَ مَرَّ رَسُولُ اللَّهِ صلى الله عليه وسلم بِشَيْخٍ يُهَادَى بَيْنَ اثْنَيْنِ فَقَالَ ‏"‏ مَا بَالُ هَذَا ‏"‏ ‏.‏ قَالُوا نَذَرَ أَنْ يَمْشِيَ ‏.‏ قَالَ ‏"‏ إِنَّ اللَّهَ غَنِيٌّ عَنْ تَعْذِيبِ هَذَا نَفْسَهُ مُرْهُ فَلْيَرْكَبْ ‏"‏ ‏.‏ فَأَمَرَهُ أَنْ يَرْكَبَ ‏.‏

It was narrated that Anas said: "The Messenger of Allah passed by an old man who was being supported between two men and said: 'What is the matter with him?' They said: 'He vowed to walk.' He said: 'Allah has no need for him to torture himself. Tell him to ride.'" So he was told to ride. Translation Not Available

Book Ref: Sunan An Nisai Book 35 Hadith 3853
Web Ref:  Sunan An Nisai Vol 4 Book 35 Hadith 3884