After the death of the two hundred and fifty followers of Korah, who perished at the offering of incense, Eleazar, the son of Aaron, was ordered "to take up the censers out of the burning," in which the souls, not the bodies of the sinners were burned,  that out of these brasen plates he made a covering for the altar. Eleazar, and not his father, the high priest, received this commission, for God said: "The censer brought death upon two of Aaron's sons, therefore let the third now fetch forth the censer and effect expiation for the sinners."  The covering of the altar fashioned out of the brass of these censers was "to be a memorial unto the children of Israel, to the end that no stranger, which is not of the seed of Aaron, come near to burn incense before the Lord." Such a one was not, however, to be punished like Korah and his company, but in the same way as Moses had once been punished by God, with leprosy. This punishment was visited upon king Uzziah, who tried to burn incense in the Temple, asserting that it was the king's task to perform the service before the King of all. The heavens hastened to the scene to consume him, just as the celestial fire had once consumed the two hundred and fifty men, who had wrongfully assumed the rights of priesthood; the earth strove to swallow him as it had once swallowed Korah and his company. But a celestial voice announced: "Upon none save Korah and his company came punishments like these, upon no others. This man's punishment shall be leprosy." Hence Uzziah became a leper. 
Peace was not, however, established with the destruction of Korah and his company, for on the very day that followed the terrible catastrophe, there arose a rebellion against Moses, that was even more violent than the preceding one. For although the people were now convinced that nothing came to pass without the will of God, still they thought God was doing all this for Moses' sake. Hence they laid at his door God's violent anger against them, blaming not the wickedness of those who had been punished, but Moses, who, they said, had excited God's revengefulness against them. They accused Moses of having brought about the death of so many of the noblest among them as a punishment for the people, only that they might not again venture to call him to account, and that he might thereby ensure his brother's possession of the priestly office, since no one would hereafter covet it, seeing that on its account the noblest among them had met so terrible a fate. The kinsmen of those who had perished stirred the flame of resentment and spurred on the people to set a limit to Moses' love of power, insisting that the public welfare and the safety of Israel demanded such measures.  These unseemly speeches and their unceasing, incorrigible perverseness brought upon them God's wrath to such a degree that He wanted to destroy them all, and bade Moses and Aaron go away from the congregation that He might instantly set about their ruin.
When Moses saw that "there was wrath gone out from the Lord, and the plague was begun," he called Aaron to him, saying: "Take thy censer and put fire therein from off the altar, and lay incense thereon, and carry it quickly unto the congregation, and make atonement for them." This remedy against death Moses had learned from the Angel of Death himself at the time he was staying in heaven to receive the Torah. At that time he had received a gift from each one of the angels, and that of the Angel of Death had been the revelation of the secret that incense can hold him at bay.  Moses, in applying this remedy, had in mind also the purpose of showing the people the injustice of their superstition concerning the offering of incense. They called it death-bearing because it had brought death upon Nadab and Abihu, as well as upon the two hundred and fifty followers of Korah. He now wished to convince them that it was this very incense that prevented the plague, and to teach them that it is sin that brings death.  Aaron, however, did not know why he employed incense, and therefore said to Moses: "O my lord Moses, hast thou perchance my death in view? My sons were burned because they put strange fires into the censers. Shall I now fetch holy fire from the altar and carry it outside? Surely I shall meet death through this fire!" Moses replied: "Go quickly and do as I have bidden thee, for while thou dost stand and talk, they die." Aaron hastened to carry out the command given to him, saying: "Even if it be my death, I obey gladly if I can only serve Israel thereby." 
The Angel of Death had meanwhile wrought terrible havoc among the people, like a reaper mowing down line after line of them, allowing not one of the line he touched to escape, whereas, on the other hand, not a single man died before he reached the row in which the man stood. Aaron, censer in hand, now appeared, and stood up between the ranks of the living and those of the dead, holding the Angel of Death at bay. The latter now addressed Aaron, saying: "Leave me to my work, for I have been sent to do it by God, whereas thou dost bid me stop in the name of a creature that is only of flesh and blood." Aaron did not, however, yield, but said: "Moses acts only as God commands him, and if thou wilt not trust him, behold, God and Moses are both in the Tabernacle, let us both betake ourselves thither." The Angel of Death refused to obey his call, whereupon Aaron seized him by force and, thrusting the censer under his face, dragged him to the Tabernacle where he locked him in, so that death ceased. 
In this way Aaron paid off a debt to Moses. After the worship of the Golden Calf, that came to pass not without some guilt on Aaron's part, God had decreed that all four of Aaron's sons were to die, but Moses stood up between the living and the dead, and through his prayer succeeded in saving two out of the four. In the same way Aaron now stood up between the living and the dead to ward off from Israel the Angel of Death. 
God in His kindness now desired the people once and for all to be convinced of the truth that Aaron was the elect, and his house the house of priesthood, hence he bade Moses convince them in the following fashion. Upon God's command, he took a beam of wood, divided it into twelve rods, bade every prince of a tribe in his own hand write his name on one of the rods respectively, and laid up the rods over night before the sanctuary. Then the miracle came to pass that the rod of Aaron, the prince of the tribe of Levi, bore the Ineffable Name which caused the rod to bloom blossoms over night and to yield ripe almonds. When the people, who all night had been pondering which tribe should on the morrow be proven by the rod of its prince to be the chosen one, betook themselves early in the morning to the sanctuary, and saw the blossoms and almonds upon the rod of Aaron, they were at last convinced that God had destined the priesthood for his house. The almonds, which ripen more quickly than any other fruit, at the same time informed them that God would quickly bring punishment upon those who should venture to usurp the powers of priesthood. Aaron's rod was then laid up before the Holy Ark by Moses. It was this rod, kings used until the time of the destruction of the Temple, when, in miraculous fashion, it disappeared. Elijah will in the future fetch it forth and hand it over to the Messiah.