Ya'la bin Mamlak narrates that he asked Sayyidah Umm Salamah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), about the prayer of the Prophet (peace and blessings be upon him), and she said: He (peace and blessings be upon him) would pray Isha, then glorify Allah, then after that pray as much of the night as Allah willed. Then he would sleep for as long as he had prayed, then wake up from that sleep and pray for as long as he had slept, and this last prayer of his (peace and blessings be upon him) would continue until the morning.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19949