John 14:27
“Peace I leave to you.”
All but saying, “What are you harmed by the trouble of the world, provided ye be at peace with Me? For this peace is not of the same kind as that. The one is external, is often mischievous and unprofitable, and is no advantage to those who possess it; but I give you peace of such a kind that you be at peace with one another, which thing renders you stronger.” And because He said again, “I leave,” which was the expression of One departing, and enough to confound them, therefore He again says,
“Let not your heart be troubled, neither let it be afraid.”
Do you see that they were affected partly by loving affection, partly by fear?
Source: Homilies on the Gospel of John (New Advent)