Musnad Abu Ya'la al-Mawsili 160:13

Abu Kurayb Muhammad ibn al-Ala narrated to us, Ibn Abi Za’idah narrated to us, from Isra’il, from ‘Isa ibn Abi ‘Azzah, from Abu Thawr al-Azdi, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) commanded me to perform the Witr prayer before I sleep. ‘Isa said: And Jabir used to perform the Witr prayer at the beginning of the night, then he would sleep.