John Gill Commentary Exodus 24:2

"and Moses alone shall come near unto Jehovah; but they shall not come near; neither shall the people go up with him." — Exodus 24:2 (ASV)

And Moses alone shall come near the Lord
Into the cloud where he was, and talks with him face to face, as a man talks with his friend; which was great nearness indeed, and a peculiar favour and high honour was this:

but they shall not come nigh ;
Aaron, Nadab, and Abihu, and the seventy elders of Israel:

neither shall the people go up with him ;
not any of them, much less the whole body. It seems, by this account, that Moses has been down from the mount after he has received the laws recorded in the two preceding chapters; though as yet he had not related them to the people, but did before he went up again by the above order, as appears from what follows.