Musannaf Ibn Abi Shayba 33:708

Muhammad ibn Fudayl narrated to us, from his father, who said: I heard Mahan say: "Is one of you not ashamed that his mount which he rides and his garment which he wears are more in remembrance [of Allah] than he is?" He used to not cease from the *takbir* (saying Allahu Akbar) and the *tahlil* (saying La ilaha illa Allah).