It is narrated from Aishah (may Allah be pleased with her), the honoured wife of the Prophet (peace and blessings be upon him): I never saw the Messenger of Allah (peace and blessings be upon him) sleeping before Isha, nor ever playing after it; either he would be engaged in remembrance (dhikr) and gain reward, or he would rest and be at peace.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2125