Albert Barnes Commentary Job 41:4

"Will he make a covenant with thee, That thou shouldest take him for a servant for ever?" — Job 41:4 (ASV)

Will he make a covenant with thee?—That is, will he submit himself to you and enter into a compact to serve you? Such a compact was made by those who agreed to serve another; and the idea here is that the animal here referred to could not be reduced to such service—that is, could not be tamed.

Wilt thou take him for a servant for ever?—Can you so subdue him that he will be a perpetual slave? The meaning of all this is that he was an untamable animal and could not be reduced, as many others could, to domestic use.