Decline the offer

You look at him and reply, "If I betray my word to the elves how can you trust me.... ? How can anyone trust me...? I think I'll stay will the elves... Your little rabble here has little chance of taking back my throne..."

He looks at you as he retakes his chair "Very well.... Since you came here in peace I will let you go, but the next time we meet I won't extend the same courtesty... It will be quite a feast for the crows...."

Just as he says he allows you to leave.... For now...