Abu Wa'il says: I heard Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) say: Keep reciting this Qur'an regularly, for it slips away from a person's chest faster than a grazing animal slips away from its tether. Then he explained: The Prophet Muhammad (peace and blessings be upon him) said: "It is extremely bad for a person to say, 'I forgot such-and-such verses,' rather, he was made to forget them."
Hadith Referenceمسند الحميدي / 91
Hadith Gradingمحدثین:إسناده صحيح
Hadith Takhrij«إسناده صحيح ، أخرجه البخاري 5039 ، 5032، ومسلم: 790، وصحيح ابن حبان: 761، 762، 763، وأبو يعلى فى "مسنده" ، برقم: 5136»