Musannaf Ibn Abi Shayba 1:1721

Hushaym narrated to us, from Mansur, from 'Ata', that an Abyssinian fell into Zamzam and died. He said: So Ibn al-Zubayr ordered that the water of Zamzam be drained. He said: The water did not cease [flowing]. He said: So they looked, and behold, there was a spring gushing from the direction of the Black Stone. He said: So Ibn al-Zubayr said, "That is enough for you."