“The priest shall command and one shall slaughter the one bird in an earthenware vessel over springwater” (Leviticus 14:5). “The priest shall command and one shall slaughter the one bird.” Why does he slaughter one and leave one? It is to say to you: Just as it is impossible for the slaughtered one to return, so it is impossible for the leprosy to return.26Just as the slaughtered bird will not come back to life, so the leprosy will not return to the individual once he has repented, if he does not return to his sinful ways.
At that moment, the Holy One blessed be He summons His legions and says: ‘It was not for nothing that I struck him, but rather, “I became angry because of his sinful thievery; I struck him…[and he went waywardly in the way of his heart]”’ (Isaiah 57:17). Rabbi Abba bar Kahan said: The vomiter had returned to his vomit, just as it says: “Like a dog that returns to its vomit” (Proverbs 26:11).27God did not strike him for nothing, but rather because “he went waywardly in the way of his heart.”
Rabbi Abba compares this to one who returns to his vomit because before this individual was afflicted with leprosy he had received divine warnings in the form of leprous marks on his house and clothing, and yet he repeated his sin (Etz Yosef). Rabbi Yehoshua ben Levi said: The fool returns to his path of folly, just as it says: “So a fool repeats his folly” (Proverbs 26:11). “I saw his ways and I will heal him; I will guide him and pay condolences to him and his mourners” (Isaiah 57:18); these are his limbs that mourn him.
“Creator of the expression [niv] of the lips” (Isaiah 57:19), Rabbi Yehoshua ben Levi said: If a person’s lips produced [henivu] prayer, he is guaranteed that his prayer is heard. What is the source? “Creator of the expression of the lips: Peace, peace [for the distant and for the near said the Lord, and I will heal him]” (Isaiah 57:19). Rabbi Yehoshua bar Naḥmani says: If one focused [kiven] his heart in prayer, he is guaranteed that his prayer will be heard, as it is stated: “Prepare [takhin] their heart, incline your ear” (Psalms 10:17).
When the punishment has been completed, he is absolved.28This is based on the double usage of the word “peace [shalom]” in the verse cited above (Isaiah 57:19). The midrash interprets this to mean that when his punishment has been completed [shelimin] he will live in peace. “For the distant” (Isaiah 57:19), Rav Huna and Rav Yudan in the name of Rav Aḥa: This is the leper, who had been distant but has drawn near.
“Said the Lord and I will heal him” (Isaiah 57:19), He will heal him Himself, as it is stated: “Heal me, Lord, and I will be healed; save me, and I will be saved…” (Jeremiah 17:14).