Answered by Shaykh Omar Qureshi
Question: For Shafi’is, when performing istanjah, is it ok to merely wipe ones anus or is it necessary for one to clean in a bit deeper?
Answer: Assalamu ‘alaikum.
In the Shafi’i school, what is required is that one remove any and all filth when performing istinja’. At minimum, one must wipe three times with a substance that is considered valid to remove filth. In our school, tissue paper is valid to use. If filth still remains after three wipes, then one must wipe as many times as need to remove the filth present. One need not be 100% certain that all of the filth has been removed. Rather, one can be generally sure that the filth has been removed. One should not clean the inside of the anus or go any deeper when performing istinja’.
Allah the Exalted knows best.
Omar