Narrated by Ibn Umar (Radhiallaho anho):
Allah’s Messenger (sallallaahu ‘alaihi wasallam), said, “The example of the person who knows the Qur’an by heart is like the owner of tied camels. If he keeps them tied, he will control them, but if he releases them, they will run away.”
Sahih Al-Bukhari Vol. 6 : No. 549

Narrated by Abu Musa(Radhiallaho anho):
Allah’s Messenger (sallallaahu ‘alaihi wasallam), said, “Keep on reciting the Qur’an, for, by Him in Whose Hand my life is, Quran runs away (is forgotten) faster than camels that are released from their
tying ropes.”
Sahih Al-Bukhari Vol. 6 : No. 552