Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates: "I visited my maternal aunt, and it happened to be the night on which the Prophet (peace and blessings be upon him) was staying with her. The Messenger of Allah (peace and blessings be upon him) got up in the last part of the night for a long while and performed ablution thoroughly, then stood up to pray. I too got up, performed ablution and came and stood at his (peace and blessings be upon him) side. When he (peace and blessings be upon him) realized that I wanted to pray, he (peace and blessings be upon him) took me by the hand and made me stand on his right side. The Messenger of Allah (peace and blessings be upon him) prayed and performed witr with seven or nine rak'ahs, then prayed two rak'ahs, then lay down on his side until I heard the sound of his (peace and blessings be upon him) snoring. Then the iqamah for the prayer was called, and he (peace and blessings be upon him) went out to the prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12725