Kabbalah su Numeri 3:4

Another explanation for, "After the death of the two sons of Aaron." Rabbi Yosi said: It should have read, 'After the death of Nadab and Abihu,' so what is the reason (that it says) "The two sons of Aaron?" It is obvious that they were his sons. We have learned that until that time they were not adults but still under the authority of their father. Hence, "when they came near before Hashem, and died" (Vayikra 16:1), they were rushing the time (of offering incense) during the lifetime of their father, and there was more, because of the sin they committed "when they offered a foreign fire" (Bemidbar 3:4) as we learned, in one place it is written, "When they offered a foreign fire." In another place, it is written, "When they came near before Hashem," (The combination of) both matters (caused their deaths), and so it is written here, "The two sons of Aaron". It is written, "When they came near".