And Jethro said to Moses: “Go for peace” (Exod. 3:18). You find that everyone about whom it is written Go for peace departs and returns in peace, and that everyone concerning whom it is said Go in peace departs but does not return (in peace). Jethro said to Moses: Go for peace. And he departed and he returned in peace.
Jethro on to Moses Go for Peace in Shemot
Midrash Tanchuma, Shemot 21