John 14:27 - Coke's Commentary on the Holy Bible

Peace I leave with you:— "Peace be to you" was the common salutation and compliment mutually given by the Jews to each other at meeting and parting. But although this compliment implied a wish of every thing thatcould make one happy, it was often used without any meaning. At best, it was but a wish, however sincere, and had no real efficacy in making him to whom it was given happy. But in the mouth of Jesus, by whose wisdom and power the affairs of the world are governed, a farewel wish was a matter of a very different kind: His peace, his parting blessing could draw down all manner of felicity upon those who were the objects of it. Accordingly, he encouraged his disciples from that consideration, under the prospect of his departure; desiring them not to be in the least anxious about what was to befal them after he was gone. See the note on Matthew 10:13.