Sayyiduna Ubaydah al-Mulayki (may Allah be pleased with him) reported this saying of the Prophet (peace and blessings be upon him): "O people of the Qur'an! Do not make the Qur'an a pillow. Recite it as it deserves to be recited in the hours of the night and the day, and remember what is mentioned in it (or take admonition from it) so that you may be successful. And do not hasten its reward, for it does have a reward."
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Abu Bakr bin Abi Maryam, who is da'if (weak).