Adam Clarke on Exodus 24:1

Come up unto the Lord - Moses and Aaron were already on the mount, or at least some way up, (Exo 19:24), where they had heard the voice of the Lord distinctly speaking to them: and the people also saw and heard, but in a less distinct manner, probably like the hoarse grumbling sound of distant thunder; see Exo 20:18. Calmet, who complains of the apparent want of order in the facts laid down here, thinks the whole should be understood thus: - "After God had laid before Moses and Aaron all the laws mentioned from the beginning of the 20th chapter to the end of the 23d, before they went down from the mount to lay them before the people, he told them that, when they had proposed the conditions of the covenant to the Israelites, and they had ratified them, they were to come up again unto the mountain accompanied with Nadab and Abihu the sons of Aaron, and seventy of the principal elders of Israel. Moses accordingly went down, spoke to the people, ratified the covenant, and then, according to the command of God mentioned here, he and the others reascended the mountain. Tout cela est racont ici avec assez peu d'ordre."