Albert Barnes Commentary Job 41:8

"Lay thy hand upon him; Remember the battle, and do so no more." — Job 41:8 (ASV)

Lay your hand upon him - Professor Lee renders this, very improperly, as it seems to me, “Lay your hand on your mouth respecting him,” supposing it means that he should be awed into silence by dread of the animal referred to. But the meaning of the passage evidently is, “Endeavor to seize him by laying the hand on him, and you will soon desist from the fearful conflict, and will not renew it.”

Remember the battle - Remember what a fearful conflict will ensue. Perhaps there is an allusion to some fact fresh in the mind of Job, where such an attempt had been made to secure the leviathan, attended with fearful disaster to those who had made the attempt.

Do no more - Or, rather, “You will not do it again.” That is, he would be deterred from ever renewing the attempt, or the conflict would be fatal to him.