Musnad Ahmad 1009:3

Abdullah narrated to us, Ubaydullah ibn Umar al-Qawariri narrated to me, Abdullah ibn Ja’far narrated to us, Muhammad ibn Yusuf informed me, from Abdullah ibn al-Fadl, from Abu Bakr ibn Abd al-Rahman ibn al-Harith, from Safwan ibn al-Mu’attal al-Sulami, who said: I was with the Messenger of Allah (peace and blessings of Allah be upon him) on a journey, and I observed his prayer one night. He prayed the final Isha prayer, then he slept. When it was the middle of the night, he woke up and recited the ten verses from the end of Surah Al-Imran. Then he used the miswak, then he performed wudu, then he stood and prayed two rak'ahs; I do not know whether his standing, his bowing, or his prostration was longer. Then he finished and slept. Then he woke up and recited the verses, then he used the miswak, then he performed wudu, then he stood and prayed two rak'ahs; I do not know whether his standing, his bowing, or his prostration was longer. Then he finished and slept. Then he woke up and did that, and he continued to do as he did the first time until he had prayed eleven rak'ahs.