Exodus 17:12

17:12 When the hands of Moses became heavy, they took a stone and put it under him, and Aaron and Hur held up his hands, one on one side and one on the other, and so his hands were steady until the sun went down.

Exodus 18:22

18:22 They will judge the people under normal circumstances, and every difficult case they will bring to you, but every small case they themselves will judge, so that you may make it easier for yourself, and they will bear the burden with you.