Mishnà su Levitico 14:28

[The priest] then took some [of the contents] of the log of oil and poured it into his colleague's hand; And if he poured it into his own hand, the obligation is fulfilled. He then dipped [his right forefinger] in the oil and sprinkled it seven times towards the Holy of Holies, dipping it for every sprinkling. He then approached the metzora, to the same places that he applied the blood he now applied the oil, as it is said, "Over the same places as the blood of the guilt offering; 29 and what is left of the oil in his palm the priest shall put on the head of the one being cleansed, to make expiation for him before the Lord." (Leviticus 14:28-29). If he "put upon," he has made atonement, but if he did not "put upon," he did not make atonement, the words of Rabbi Akiba. Rabbi Yohanan ben Nuri says: these are but the remainders of the mitzvah. Whether he "put upon" or did not "put upon," atonement is made, only it is accounted to him as if he did not make atonement. If any oil was missing from the log before it was poured out it may be filled up again; if after it was poured out, other oil must be brought anew, the words of Rabbi Akiva. Rabbi Shimon says: if any oil was missing from the log before it was applied, it may be filled up; but if after it had been applied, other oil must be brought anew.