Rabbi Shimon Bar Yochai, Translation:Zohar — Vol. III Leviticus-Numbers-Deuteronomy
“ But Nadab and Abihu by themselves are each considered equal to the seventy members of the Sanhedrin who served before Moses. For this reason, their deaths atoned for Yisrael. Therefore, it is written, "But let your brethren, the whole house of Yisrael bewail the burning" (Vayikra 10:6) . Rabbi Shimon said: "Nadab the firstborn," meaning he is the one that all acclaim and praise are his. How much more so with Nadab and Abihu (together) , because these two have no equal among all Yisrael. "And Hashem spoke to Moses after the death of the two sons of Aaron" (Vayikra 16:1) . ”
