John Gill 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
If you can or dare. 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 you will have no share with this creature:

do no more ;
if you can by any means escape, take care never to do the like again; or you will never do so any more, you will certainly die for it.