“He said to Moses, “Come up to Yahweh.” If not read carefully in context this verse can be confusing because it sounds like God is calling Moses to go up Mount Sinai. But Moses is already up Mount Sinai; he went up for the fourth time in Exodus 20:21). So this command here in Exodus 24:1 came during Moses’ fourth time up Mount Sinai to be with Yahweh (see commentary on Exodus 20:21). God is telling Moses to come up again, but only part way, and bring Aaron, Nadab, and Abihu, and 70 of the elders of Israel along too. But those men were down at the foot of the mountain, so Moses has to go down again to get those men and bring them part way up with them. So Moses went back down to get them (Exod. 24:3) and brought them partway up Mount Sinai as God asked him to do (Exod. 24:9).
That Moses was still up on Mount Sinai when God told him to bring Aaron and the other men part way up the mountain would have been much clearer if Exodus 24:1 had not been made into a new chapter. This is one of the many places in the Bible where the chapter division is put in a place that makes the Bible difficult and confusing to read. The chapter divisions and verse divisions were added to the Bible by people who lived many hundreds of years after the Bible text itself was written down.
[For more on Moses’ seven trips up Mount Sinai, see commentary on Exod. 19:3.]
“bow down.” The common biblical way of bowing down before people or God was to fall to one’s knees and bow the upper body to the earth. It is the same Hebrew word as “worship.”
[For more on bowing down, see commentary on 1 Chron. 29:20.]