I spent the night at my aunt Maymuna's house. The Messenger of Allah ﷺ arrived after nightfall and asked, "Has the boy prayed?"They replied, "Yes."He then lay down to rest. After as much of the night had passed as Allah willed, he got up, performed ablution, and prayed seven or five units, making them his witr prayer, and he did not give the closing salutation except at the end of them.
حدثنا عثمان بن أبي شيبة حدثنا وكيع حدثنا محمد بن قيس الأسدي عن الحكم بن عتيبة عن سعيد بن جبير
بت عند خالتي ميمونة فجاء رسول الله ﷺ بعدما أمسى فقال أصلى الغلام قالوا نعم فاضطجع حتى إذا مضى من الليل ما شاء الله قام فتوضأ ثم صلى سبعا أو خمسا أوتر بهن لم يسلم إلا في آخرهن
No references are available.
This was collected by Bukhari, see the following hadith, and Ahmad narrated it in 1/354 from Waki with the same wording.