The Quran warns those who hoard gold and silver without fulfilling their due obligation:
وَالَّذِينَ يَكْنِزُونَ الذَّهَبَ وَالْفِضَّةَ وَلَا يُنْفِقُونَهَا فِي سَبِيلِ اللَّهِ
Translation: Those who accumulate gold and silver and do not spend them in the way of Allah… (Quran 9:34, relevant excerpt).
The Hanafis invoke the general zakat texts together with narrations about jewelry. Those exempting permissible ornaments differ in how they characterize personal-use property and read the specific evidence.