Exodus 24:14

And to the sages he had said, Expect us here, at the time of our return to you; and, behold, Aharon and Hur are with you; if there be any matter of judgment, bring it to them.

AND UNTO THE ELDERS HE SAID: ‘TARRY YE HERE FOR US.’ The meaning of this is that when Moses parted from them with his minister, he commanded them that they should tarry there. It does not mean that they were to stay there day and night until their return, for he said, and behold, Aaron and Hur are with you; whosoever hath a cause, let him come near unto them, and it is in the camp that parties to a dispute would be found, since that was where the seat of justice was, and he had already told everybody, Return ye to your tents. But the meaning of tarry ye here is that they should stay at that place, and should not break through to come up to them, even to the place where Joshua was, until he [Moses] would come back to them.
In my opinion it is possible that the explanation of the verse is as follows: “Sit [translated as “tarry”] in its literal meaning: “sit” — sit in court in our place and act as a substitute for us. in our place and serve as a substitute for us in the camp; Aaron and Hur are with you, and whosoever hath a cause — one of those hard causes that they would bring to me — let him come near unto them in my place.” He said unto them as a special recognition to Aaron and Hur, for they were to come before all the elders and they would all be assembled at one place, just as he said Aaron and Hur are with you. Thus Moses commanded that the elders together with Aaron and Hur should sit as a court, just as he himself did, over the officers of thousands and hundreds, until he returns, since he knew that he would tarry in the mountain. He said: for us [tarry ye here ‘for us’] as a mark of honor to his disciple, just as he said to Joshua, Choose us out men. This is a correct interpretation. But Rashi wrote: “And unto the elders he said — when he left the camp, Tarry ye here for us — stay you with the rest of the people so as to be ready to judge each man’s dispute.” But this is impossible, for they were not at that moment in the camp, and what sense would there be for him to tell them so when they were in the camp and had already been appointed as judges!
Terumah

ואל הזקנים אמר, when he departed from them in order to ascend to the top of the mountain as G’d had commanded him in verse 12.