Mus'ab bin Sa'd narrates: I asked my father: "O my father, what is your view about this statement of Allah Almighty? (The Exalted says:) 'Those who are heedless of their prayers.' Which of us is not overtaken by forgetfulness, and which of us does not get lost in his own thoughts?" He said: "That is not what is meant. What is meant is wasting the time: that a person stays occupied with other things until the (prescribed) time (of the prayer) is wasted." In another narration the words are: Sayyiduna Sa'd (may Allah be pleased with him) said: "Does not every one of us do that?"
Abu Ya'la recorded it, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1824