So Moses' father-in-law said to him, "The thing that you do is not good.
Exodus 18:17
Surrounding context
18:16 When they have a difficulty, they come to me, and I judge between one and another; and I make known the statutes of God and His laws."
18:17 So Moses' father-in-law said to him, "The thing that you do is not good.
18:18 Both you and these people who are with you will surely wear yourselves out. For this thing is too much for you; you are not able to perform it by yourself.