Duaa-Concerning Journeys

When biding farewell to someone going off on a journey, recite:
أَسْتَوْدِعُ اللَّهَ دِينَكَ وَأَمَانَتَكَ وَخَوَاتِيمَ عَمَلِكَ
"(I make) Allah responsible for your deen, your trustworthiness and for the results of your actions".

(Tirmifhi)