Philippians 6 Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. 7 And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus.
"I bought a nice leather journal for my missionary and wrote these on the first two pages. He loves it and tells me all the time how comforting these scriptures are!" Sounds like this might be handy to have.