The dua for journey safety is: 'Astawdi'ullaha dinaka wa amanataka wa khawatima 'amalik' — I entrust to Allah your religion, your trusts, and the conclusions of your deeds. The Prophet would say this to companions departing on a journey, entrusting their most precious matters to Allah's care.
أَسْتَوْدِعُكَ اللَّهَ الَّذِي لَا تَضِيعُ وَدَائِعُهُ
Astawdi'ukallaha-lladhi la tadi'u wada'i'uh.
Meaning: I entrust you to Allah, Whose trusts are never lost.
Source: Sunan Abu Dawud #2600This dua entrusts the most important aspects of a person's life to Allah: their faith (din), their trusts and responsibilities (amanah), and the final outcomes of their deeds (khawatim). The Prophet (peace be upon him) taught that what is entrusted to Allah is never lost, providing immense comfort to travelers and those they leave behind.
أَسْتَوْدِعُكَ اللَّهَ الَّذِي لَا تَضِيعُ وَدَائِعُهُ
When the Prophet (peace be upon him) would bid farewell to a companion, he would say: 'Astawdi'ullaha dinaka wa amanataka wa khawatima 'amalik' — I entrust to Allah your religion, your trusts, and the conclusions of your deeds.