that impurity has come upon it. This is the second condition. The evidence is the hadith of Ibn Mas‘ud, may Allah be pleased with him: the Prophet, peace and blessings be upon him, threw away the piece of dung and said, “This is impure.” Riks means that which is impure.
In the hadith of Abu Hurayrah, may Allah be pleased with him, the Messenger of Allah, peace and blessings be upon him, forbade cleansing oneself with a bone or dung, saying, “They do not purify.” (1) This indicates that what is used for cleansing oneself must be pure.
Another rationale is that impurity is foul, so how could it be a means of purification?
Effective in cleansing …
His statement, “effective in cleansing,” means that it must accomplish cleansing. If it does not cleanse effectively, it is insufficient. This is the third condition.
For the purpose of cleansing oneself with stones is to remove the impurity, as shown by the fact that the Prophet, peace and blessings be upon him, forbade cleansing oneself with fewer than three stones. Also, concerning the one punished in his grave, the Prophet, peace and blessings be upon him, said: “He did not take due precautions against his urine” (2), or “He did not shield himself from urine” (3), or “He did not ensure that his urine had ceased” (4). These are three narrations.