Mukhtasar Muslim

Narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) saw an old man who was walking between his two sons, leaning on them. The Prophet (peace be upon him) asked, "What has happened to him?" The people said, "He has vowed to walk on foot." The Prophet (peace be upon him) said, "Allah is not in need of him punishing himself," and the Prophet (peace be upon him) ordered him to ride.