What is the minimum limit of the Quranic text that requires Wudu to touch according to the text?

Ablution (الوضوء): The Legal Types of Ablution

• A complete Juz (para).
• Only a complete bound copy of the Quran.
• Even a single written verse (Ayah) of the Quran.
• Touching never requires Wudu; it is only recommended.