Musannaf Ibn Abi Shayba 3:3924

6301. Affan narrated to us, he said: Bukayr ibn Abi al-Sumayt narrated to us, he said: Qatadah narrated to us regarding His saying—Exalted is He—: "They used to sleep but little of the night." He said: Al-Hasan used to say: "They used to sleep but little of the night." And Mutarrif ibn Abdullah used to say: "There was no night but that they would attain a portion of it [in prayer]." And Muhammad ibn Ali used to say: "They would not sleep until they had prayed the 'Atamah [the night prayer]."