Jamieson, Fausset and Brown on John 14:27

27. Peace I leave with you, my peace I give unto you--If Joh 14:25, 26 sounded like a note of preparation for drawing the discourse to a close, this would sound like a farewell. But oh, how different from ordinary adieus! It is a parting word, but of richest import, the customary "peace" of a parting friend sublimed and transfigured. As "the Prince of Peace" (Is 9:6) He brought it into flesh, carried it about in His Own Person ("My peace") died to make it ours, left it as the heritage of His disciples upon earth, implants and maintains it by His Spirit in their hearts. Many a legacy is "left" that is never "given" to the legatee, many a gift destined that never reaches its proper object. But Christ is the Executor of His own Testament; the peace He "leaves" He "gives"; Thus all is secure.

not as the world giveth--in contrast with the world, He gives sincerely, substantially, eternally.