Musnad Ahmad 1153:1471

Yazid narrated to us, he said: Muhammad ibn ‘Amr informed us, from Abu Salamah, from ‘Aishah, she said: I used to sleep lying across in front of the Messenger of Allah, may Allah bless him and grant him peace, while he was praying. When he intended to perform the Witr, he would nudge me with his foot and say: "Move aside."