Abdullah bin Abi Qays said: I asked Sayyidah Aishah (may Allah be pleased with her) about the witr of the Messenger of Allah (peace and blessings be upon him): did he pray witr at the beginning of the night or in the last part of the night? She said: He did both; sometimes he prayed witr at the beginning of the night and sometimes in the last part of the night. I said: All praise belongs to the One who has made room in the matter. I said: How was his (peace and blessings be upon him) recitation at night? Did he (peace and blessings be upon him) recite aloud at night or quietly? She said: He did both; sometimes he recited quietly and sometimes aloud. I said: All praise belongs to the One who has made room in the matter. Then I said: What did he do in a state of janabah? Did he perform the ritual bath before sleeping, or sleep before performing the ritual bath? She said: He did both; sometimes he (peace and blessings be upon him) performed the ritual bath and then slept, and sometimes he (peace and blessings be upon him) performed ablution and then slept. I said: All praise belongs to the One who has made room in the matter.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 969