Reference : Hisn al-Muslim 212

أَسْتَـوْدِعُ اللَّهَ ديـنَكَ
وَأَمانَتَـكَ، 
وَخَـواتيـمَ عَمَـلِك
Astawdi`ullāha dīnak, 
wa amānatak, 
wa khawātīma `amalik.


I leave your religion in the care of Allah, 
as well as your safety, 
and the last of your deeds.

Reference:
Ahmad 2/7, At-Tirmidhi 5/499. See also Al-Albani, Sahih At-Tirmidhi 2/155.

Chapter: Supplication of the resident for the traveller