The Prophet ﷺ used to pray two rakahs after the witr.
حدثنا محمد بن بشار حدثنا حماد بن مسعدة عن ميمون بن موسى المرئي عن الحسن عن أمه
أن النبي ﷺ كان يصلي بعد الوتر ركعتين
No references are available.
Sourcing, sahih. Ibn Majah also narrated it, no. 1195, from Muhammad bin Bashshar with the same wording. The hadith has many corroborating narrations, in Muslim, no. 126/738, and elsewhere. The hadith of Abu Umama [Ahmad, 5/260, 269] and Ayesha [Muslim, no. 738b].