Sahih Bukhari Volume 3, Book 28, Hadith 1866

حَدَّثَنَا مُحَمَّدُ ابْنُ سَلاَمٍ، أَخْبَرَنَا الْفَزَارِيُّ، عَنْ حُمَيْدٍ الطَّوِيلِ، قَالَ حَدَّثَنِي ثَابِتٌ، عَنْ أَنَسٍ ـ رضى الله عنه ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم رَأَى شَيْخًا يُهَادَى بَيْنَ ابْنَيْهِ قَالَ ‏"‏ مَا بَالُ هَذَا ‏"‏‏.‏ قَالُوا نَذَرَ أَنْ يَمْشِيَ‏.‏ قَالَ ‏"‏ إِنَّ اللَّهَ عَنْ تَعْذِيبِ هَذَا نَفْسَهُ لَغَنِيٌّ ‏"‏‏.‏ وَأَمَرَهُ أَنْ يَرْكَبَ‏

Narrated By Anas : The Prophet saw an old man walking, supported by his two sons, and asked about him. The people informed him that he had vowed to go on foot (to the Ka'ba). He said, "Allah is not in need of this old man's torturing himself," and ordered him to ride.