The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, narrated to me from Abu al-Qasim Ja'far ibn Muhammad, from Muhammad ibn Ya'qub, from Muhammad ibn Yahya, who raised it to Abu Abdullah عليه السلام, who said: Imam عليه السلام said: "Water is not rendered impure except by something that has flowing blood (najs sa'il)."