For example...
For example, if you want to clean the clothes that you will wear to meet an important personality or to attend a wedding or an inauguration ceremony, what exactly will you clean that outfit from? There is no doubt that you will clean and purify it from dirt, spots, wrinkles, odor, and its like so that the outfit will be ready and in the best shape possible.
Another example: If you want to clean a knife or a pair of scissors that will be used in a surgical operation on a human body, what will you clean that knife or scissors from? In this case, you will be sanitizing it from germs, microbes, and viruses. This will be your main concern so that the wound of the patient does not get contaminated and lead to death of the patient due to his contaminated wound.
Thus, after the process of sanitization and purification, the knife or scissors will become qualified to perform its duty, which requires a great amount of efficiency and care as possible. We can present lots of similar examples from our daily lives from which we can draw the conclusion that there is a definite and direct relationship between the task that will be carried out by the Mutahar and the things that it will be purified from.
In other words, the process of Tat-heer is essentially for the purpose of making the Mutahar more fit and proficient in carrying out its ask in the best form possible. This is logical, reasonable, and very clear as we use it many times in our daily lives. We clean and purify an object from the things that may hinder its performance, and therefore, it will be more successful at doing its job.
Let us now apply this same logic to our proposed question, as we will find that the purification of our Prophets, Messengers, Awsiya', and Imams (AS) should be from the things that may prevent or hinder their performance of their God-given roles. This purification should result in them being more proficient and capable of successfully fulfilling their jobs and responsibilities.
So, in order for us to know what they will be purified from, we must first identify and specify their jobs and responsibilities. We must know what its consequences and implications are so that we can logically deduce the answer based on our expectations. Now, what exactly are the roles and responsibilities of the Prophets, Messengers, Awsiya', and Imams? First : Relay and convey the orders and commands of Allah (SWT) to the people.