Musnad Ahmad 1153:440

Ishaq narrated to us, he said: Layth ibn Sa’d narrated to me, he said: Mu’awiyah ibn Salih al-Hadrami narrated to me, from ‘Abdullah ibn Qays, who said: I asked ‘Aishah: Did the Prophet, peace and blessings of Allah be upon him, perform Witr at the beginning of the night or at its end? She said: "He used to do all of that. Sometimes he would perform Witr at the beginning of the night, and sometimes he would perform Witr at its end." I said: "Praise be to Allah who has placed ease in the matter." I said: "How was his recitation? Would he recite silently or aloud?" She said: "He used to do all of that. Sometimes he would recite silently, and sometimes he would recite aloud." I said: "Praise be to Allah who has placed ease in the matter." He said: I said: "What did he used to do regarding Janabah (major ritual impurity)? Would he perform Ghusl (full ablution) before he slept, or would he sleep before he performed Ghusl?" She said: "He used to do all of that. Sometimes he would perform Ghusl then sleep, and sometimes he would perform Wudu (ablution) then sleep." I said: "Praise be to Allah who has placed ease in the matter."