Musnad Ahmad 27:1393

Waki’ narrated to us, Abdullah ibn Nafi’ narrated to me, from his father, from Ibn Umar: "That the Prophet, peace and blessings of Allah be upon him, was brought *fadikh* (a type of date beverage) at the Mosque of Fadikh, and he drank it." And that is why it was named [the Mosque of Fadikh].