Sayyidah Aishah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) used to pray eleven rak'ahs at night, one of which was witr. When he (peace and blessings be upon him) finished it, he would lie down on his right side until the mu'adhdhin came, then he would pray two light rak'ahs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4885