Charles Ellicott Commentary Exodus 24:13

"And Moses rose up, and Joshua his minister: and Moses went up into the mount of God." — Exodus 24:13 (ASV)

Moses rose up, and his minister Joshua. —The close connection of Joshua with Moses is here, for the first time, indicated. His employment as a general against Amalek (Exodus 17:9–13) might have simply marked his military capacity; but from this point in the history it becomes apparent that he was Moses’ most trusted friend and assistant in all matters where confidential relations were needed between the leader and his subordinates, and thus that he was to be his successor (Exodus 33:11; Numbers 13:8; Numbers 13:16; Numbers 27:18–23; Deuteronomy 34:9), since no other person stood in any such close association.

Moses went up into the mount of God. —Ascended, i.e., to the highest point of the mountain, of which mention has been previously made; not, probably, to the Jebel Musa, but to the highest summit of the Ras Sufsafeh, upon which the cloud rested.