Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Learn the Qur'an, recite it in a beautiful voice, and preserve it by memorising it. By the One in whose Hand is my soul, it escapes from the breasts even faster than tethered pregnant she-camels break loose from their ropes."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14873