Musannaf Ibn Abi Shayba 3:6195

Zayd ibn al-Hubab narrated to us, from al-Harith, from Musa ibn Ali, who said: I heard my father say: I heard Uqbah ibn Amir say: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: "Learn the Quran and recite it, for by the One in whose hand is my soul, it is more prone to escaping from the hearts of men than camels are from their hobbles."