From him, from Muhammad ibn Isma'il ibn Bazi’, who said: I wrote to someone to ask (Imam عليه السلام) about a pond that collects rainwater and is also supplied with water from a well. People use it for istinja (purification after relieving oneself) from urine, or a person in a state of janabah (major impurity) bathes in it. What is the limit beyond which it is not permissible to use? Imam عليه السلام wrote back: "Do not perform wudu (ablution) with such water except in cases of necessity."