Musnad Ahmad 25:1311

Husayn narrated to us, Shu'bah narrated to us, from al-Hakam, from Ibn Jubayr, from Ibn Abbas, who said: I spent the night at the house of my maternal aunt Maymunah, the wife of the Prophet, may Allah bless him and grant him peace. The Messenger of Allah, may Allah bless him and grant him peace, prayed the Isha prayer, then he came and prayed four [rak'ahs], then he slept. Then he stood and prayed four [rak'ahs], and he said: "Has the young boy slept?" — or a word similar to it. He said: So I came and stood on his left, and he placed me on his right. Then he prayed five rak'ahs, then two rak'ahs, then he slept until I heard his snoring — or his wheezing — then he went out to the prayer.