Musnad Ahmad 30:1738

Sulayman narrated to us, Isma'il narrated to us, 'Amr informed me, from 'Abd al-Rahman al-A'raj, from Abu Hurayrah, that the Prophet, peace and blessings of Allah be upon him, encountered an old man walking between his two sons, leaning upon them. The Prophet, peace and blessings of Allah be upon him, said: "What is the matter with this old man?" His two sons said: "O Messenger of Allah, he had a vow upon him." He said to him: "Ride, O old man, for Allah, the Almighty and Majestic, is in no need of you or your vow."