1. When the traveller is departing, then he should bid farewell to his family through reciting the following dua:

أَسْتَوْدِعُكَ اللهَ الَّذِيْ لَا تَضِيْعَ وَدَائِعُهُ

I entrust you to Allah, the One whose trusts are never destroyed. ^[1]

2. The family of the traveller should recite the following dua when bidding him farewell:

أَسْتَوْدِعُ اللهَ دِيْنَكَ وَأَمَانَتَكَ وَخَوَاتِيْمَ عَمَلِكَ

I place your Deen, your trust (wife, children and subordinates) and your final actions (at the time of death) in the care and trust of Allah Ta‘ala. ^[2]