Peace be upon you. Regarding your question, both Ayatollah Sistani and Ayatollah Khamenei state that istinja (the act of cleaning oneself after using the toilet) is specifically for the purification of the private parts after urination and defecation. In the case of excrement, the individual has the option to either wash it with water or wipe it with a cloth that is capable of removing impurity, with further details available in the relevant texts. However, for the ground contaminated by excrement, it cannot be purified by merely wiping it with a cloth; it must be washed with water after the impurity has been removed. Additionally, Ayatollah Sistani emphasizes that the water used for washing (if using a small amount) is considered impure as a precaution, while Ayatollah Khamenei states it is impure (as a ruling). For more information, you can refer to the official websites of both scholars.