Lay thine hand upon him - Prof. Lee renders this, very improperly, as it seems to me, "Lay thine hand on thy 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, "Thou wilt not do it again." That is, he would be deterred from ever renewing the attempt, or the conflict would be fatal to him.

Lay thine hand upon him? - Mr. Heath translates, "Be sure thou strike home. Mind thy blow: rely not upon a second stroke." Mr. Good translates: -
"Make ready thy hand against him.
Dare the contest: be firm."
He is a dangerous animal; when thou attackest him, be sure of thy advantage; if thou miss, thou art ruined. Depend not on other advantages, if thou miss the first. Kill him at once, or he will kill thee.

Lay thine hand upon him, remember (o) the battle, do no more.
(o) If you once consider the danger, you will not meddle with him.

Lay thine hand upon him,.... If thou canst or darest. It is dangerous so to do, either to the whale or crocodile;
remember the battle; or "look for war", as Mr. Broughton renders it; expect a fight will ensue, in which thou wilt have no share with this creature:
do no more; if thou canst by any means escape, take care never to do the like again; or thou wilt never do so any more, thou wilt certainly die for it.

If thou lay . . . thou wilt have reason ever to remember . . . and thou wilt never try it again.

Lay - Seize upon him, if thou darest. Battle - But ere thou attempt it consider what thou art doing, and with whom, thou art going to fight. Do no more - Proceed no farther, draw back thy hand.