Matthew Poole and continuators on Numbers 11:24

24 And Moses went out and told the people the words of the LORD, and gathered the seventy men of the elders of the people, and set them round about the tabernacle .

Out of the tabernacle, into which he entred to receive Gods answers from the Mercy-seat, Numb. 7. 89.

Either they are called seventy from the stated number, though two of them were lacking, ver. 26. as the Apostles are called the twelve, Mat. 26. 20. when one of that number was absent: or, he is said to have gathered them, when he gave command to gather them.

Partly that the awe of God might be imprinted upon their hearts that they might more seriously undertake and more faithfully manage their high employment, partly to gain them the more authority and respect from the people, and principally, because that was the place where God manifested himself and gave his blessings, and therefore there he would bestow his spirit upon them.