Rabbi Yehuda and Rabbi Shimon discuss the words 'spoke' and 'said' in "Hashem spoke to Moses" and "Hashem said to Moses" and we learn that they are from two levels, judgment and mercy, but nevertheless are from the same source, that is Zeir Anpin. Rabbi Yitzchak says that one verse says to serve Hashem in fear and another says to come before him with singing, and that these two verses seem contradictory. Rabbi Shimon says that if one shows awe and reverence, he will then deserve the joy and singing. One should not rejoice too much over worldly matters, so that he will be able to perform the precepts with gladness. We are told that fear of God is the beginning of service to Him. We read of the several reasons that Nadab and Abihu died while giving the offering, and that they were still under the authority of Aaron at the time. Rabbi Chiya tells how he encountered two men studying the Torah in a cleft in the mountain, and of how they were discussing poems and psalms and songs, and speaking about the sons of Korah who did not die. They say that every time a righteous person dies it brings forgiveness for the sins of the whole generation. The memory of the two sons of Aaron serves as atonement for Yisrael while they are in exile, because Nadab and Abihu are each considered equal to the seventy members of the Sanhedrin who served before Moses.