Musannaf Ibn Abi Shayba 1:1753

Ibn ‘Ulayyah narrated to us, from Shu’bah, who said: I asked al-Hakam about a man who cleared his throat, and his phlegm fell into his purification water. He said: "He takes it like this and throws it away." And Shu’bah gestured with his hand, describing that he scoops it out of the vessel and throws it away.