'A'isha observed that the Messenger of Allah ﷺ used to observe prayer in the night and the last of his (night) prayer was Witr. (Using translation from Muslim 740)
كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ حَتَّى يَكُونَ آخِرَ صَلَاتِهِ الْوَتْرُ
'A'isha observed that the Messenger of Allah ﷺ used to observe prayer in the night and the last of his (night) prayer was Witr.
كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ حَتَّى يَكُونَ آخِرَ صَلاَتِهِ الْوِتْرُ
"The Messenger of Allah ﷺ used to pray nine rak'ahs at night." (Using translation from Nasāʾī 1725)
أَنَّهَا قَالَتْ كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ تِسْعَ رَكَعَاتٍ
"The Messenger of Allah ﷺ used to pray nine rak'ahs at night." (Using translation from Nasāʾī 1725)
كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ تِسْعَ رَكَعَاتٍ
[Machine] The Messenger of Allah ﷺ used to pray at night until the last prayer of his was Witr.
كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ حَتَّى يَكُونَ آخِرُ صَلَاتِهِ الْوِتْرَ