A.T. Robertson Commentary John 14:27

"Peace I leave with you; my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be fearful." — John 14:27 (ASV)

My peace (ειρηνην την εμην). This is Christ's bequest to the disciples before he goes, the shalom of the orient for greeting and parting, used by Jesus in his appearances after the resurrection (20:19,21,26) as in 2 John 1:3; 3 John 1:14, but here and in 16:33 in the sense of spiritual peace such as only Christ can give and which his Incarnation offers to men (Luke 2:14).

Neither let it be fearful (μεδη δειλιατω). Added to the prohibition in verse 1, only N.T. example of δειλιαω (rare word in Aristotle, in a papyrus of one condemned to death), common in LXX, like palpitating of the heart (from δειλος).