I asked 'Aishah about the witr observes by the Messenger of Allah ﷺ. She replied: Sometime he observed the witr prayer in the early hours of the night, sometimes he observed it at the end of it. I asked: How did he recite the Qur'an ? Did he recite the Qur'an quietly or loudly ? She replied: He did it in any way. Sometimes he recited quietly and sometimes loudly, sometimes he took bath and then slept and sometimes he performed ablution and then slept. Abu Dawud said: The narrators other than Qutaibah said: This refer to his bath due to sexual defilement. (Using translation from Abū Dāʾūd 1437)   

وِتْرِ رَسُولِ اللهِ ﷺ قَالَتْ رُبَّمَا أَوْتَرَ مِنْ أَوَّلِ اللَّيْلِ وَرُبَّمَا أَوْتَرَ مِنْ آخِرِهِ قُلْتُ كَيْفَ كَانَتْ قِرَاءَتُهُ كَانَ يُسِرُّ بِالْقِرَاءَةِ أَمْ يَجْهَرُ؟ قَالَتْ كُلُّ ذَلِكَ كَانَ يَفْعَلُ رُبَّمَا أَسَرَّ وَرُبَّمَا جَهَرَ وَرُبَّمَا اغْتَسَلَ وَرُبَّمَا تَوَضَّأَ فَنَامَ