What marks the genitive on Abī in ʿinda Abī Ḥanīfah?

Book of Hajj: Tawaf al-Ziyarah, Hajj Saʿi, and Second Release

• Yāʾ because it is one of the five nouns
• Wāw because it is a sound masculine plural
• Alif because it is a dual
• Sukūn because it is jussive