Musnad Ahmad 33:757

Qutaybah ibn Sa'id narrated to us, Ibn Lahi'ah narrated to us, from Abu al-Zubayr, from Jabir ibn 'Abd Allah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Increase in [the possession of] sandals, for a man continues to be as if he is riding so long as he is wearing sandals."