Commentary for Leviticus 13:44

בראשו נגעו HIS PLAGUE IS ON HIS HEAD — I have only a statement that the following laws apply to the case of נתקין, plagues on hairy places! Whence may we learn that there are included the sufferers from all other kinds of leprous plagues? Because it states מא יטמאנו‎ט, “he shall in any case proclaim him unclean” (Sifra, Tazria Parashat Nega'im, Chapter 12 2)— thus including all of these: regarding all of these it says: “his garments shall be rent etc.”.

צרוע הוא טמא הוא, he is "leprous," he is ritually impure. It appears best to approach these words in the same way Hillel approached the words טהור הוא וטהרו הכהן in verse 37. Here the force of the exegesis is even more convincing as the word צרוע refers to the body of the afflicted person whereas we still require that the priest declare him to be ritually impure. This means that legally speaking, his symptoms notwithstanding, the afflicted person would not be considered subject to the laws of impurity until the priest had declared him to be impure.

טמא הוא, טמא יטמאנו הכהן, “he is ritually impure, the priest has to declare him as impure.” In verse 37 in a parallel situation the Torah used similar syntax writing טהור הוא, וטהרו הכהן, “he is ritually pure, and the priest shall declare him as ritually pure.” From both of these verses we learn that even though the priest has observed unmistakable signs of either purity or impurity it is essential for him to confirm this by saying so. We have been taught at the end of the first chapter of the Tossephta of Nega-im that this was one of the reasons that prompted Hillel to return to the land of Israel from Babylon. He wanted to make certain that these procedures are understood and followed to the letter. He moved to Israel in order to explain the reasons for these rules to the local Rabbinical authorities.