John Calvin Commentary Exodus 18:17

"And Moses` father-in-law said unto him, The thing that thou doest is not good." — Exodus 18:17 (ASV)

And Moses’ father-in-law said. He does not absolutely condemn the whole system which Moses had previously adopted, in the manner of morose, perverse, or ambitious men who, by criticizing some minor detail, obscure the noble deeds of others; but by seeking only to correct a part of it, he does not detract from the just praise of Moses, and leaves the power which God had conferred upon him untouched. In this, his moderation is worth observing, for he does not abuse this pretext of a particular error to upset the due order of things, but only advises Moses how he may usefully execute the office which God had conferred upon him.