«إِنَّ اللَّهَ زَادَكُمْ صَلَاةً إِلَى صَلَاتِكُمْ، أَلَا وَهِيَ الْوِتْرُ، فَصَلُّوهَا مَا بَيْنَ الْعِشَاءِ إِلَى طُلُوعِ الْفَجْرِ»
Meaning: Allah has added a prayer for you, Witr; perform it between Isha and dawn.
The Hanafi argument reads the imperative “perform it” as supporting obligation. This is the reasoning given; a full hadith-authenticity investigation is a separate inquiry.