Moshe is told to warn the people again not to approach the mountain. Moshe protests that the people have already been warned. HaShem tells him that he must do so nevertheless. Then he is to return to the mountain. Aharon and the first born, who are the priests at this point, are to approach, each according to his level.
Moshe descends and passes on the information.
This is the assent foretold above, paragraph 9. During Matan Torah, Nadav, Avihu and the elders gaze inappropriately. Their punishment is postponed until another occasion, in order not to detract from Matan Torah. Matan Torah itself, the pronouncement of the 10 Statements, is in Yisro. All of the 10 were said in a single word, then HaShem repeated and explained each one individually.