'Adversary' in the Bible

and thou hast beheld an adversary in My habitation, in all that He doth good with Israel, and there is not an old man in thy house all the days.

And the heads of the Philistines are wroth against him, and the heads of the Philistines say to him, 'Send back the man, and he doth turn back unto his place whither thou hast appointed him, and doth not go down with us into battle, and is not to us for an adversary in battle; and wherewith doth this one reconcile himself unto his lord -- is it not with the heads of those men?'