Exodus 19:24
23 Moses said to the Lord, “The people are not able to come up to Mount Sinai, because you solemnly warned us, ‘Set boundaries for the mountain and set it apart.’” 24 The Lord said to him, “Go, get down, and then come up, and Aaron with you, but do not let the priests and the people force their way through to come up to the Lord, lest he break through against them.” 25 So Moses went down to the people and spoke to them.
Exodus 24:1
1 But to Moses the Lord said, “Come up to the Lord, you and Aaron, Nadab and Abihu, and seventy of the elders of Israel, and worship from a distance. 2 Moses alone may come near the Lord, but the others must not come near, nor may the people go up with him.” 3 Moses came and told the people all the Lord’s words and all the decisions. All the people answered together, “We are willing to do all the words that the Lord has said,”
Exodus 34:3
1 The Lord said to Moses, “Cut out two tablets of stone like the first, and I will write on the tablets the words that were on the first tablets, which you smashed. 2 Be prepared in the morning, and go up in the morning to Mount Sinai, and station yourself for me there on the top of the mountain. 3 No one is to come up with you; do not let anyone be seen anywhere on the mountain; not even the flocks or the herds may graze in front of that mountain.”
Notes and References
"... Exodus 19:24 ... The command that Aaron is to go up together with Moses is unexpected here in J. Aaron has never been mentioned up to this point in J. In fact, Aaron is never mentioned at all in J outside of this verse. Moreover, Aaron does not in fact go up with Moses in J. The next time that Moses goes up the mountain in J, God tells him, “No man shall go up with you” (Exodus 34:3). It is rather in E that Aaron (and others) will go up with Moses (Exodus 24:1). Therefore, it appears that a redactor has added here in order to deal with the fact that Moses’ ascent in E along with Aaron and other Persons is now inserted before the J account of an ascent that Moses makes alone in Exodus 34. The redactor who made this addition could be either R or RJE ..."
Friedman, Richard Elliott The Bible with Sources Revealed: A New View Into the Five Books of Moses (pp. 152-153) Harper San Francisco, 2005