It is narrated from Imam (peace be upon him): When you intend to travel, buy your safety from your Lord (i.e., give charity) with whatever amount your heart desires (as much as you can afford). Then give that charity and say:

بِسْمِ اﷲِ الرَّحْمٰنِ الرَّحِیْمِ

Bismillaahir-Rahmaanir-Raheem

In the name of Allah the Beneficent the Merciful.

اَللّٰھُمَّ إِنِّي أُريدُ سَفَرَ (كَذَا وَكَذَا) وَ إِنِّي قَدِ اشْتَرَيْتُ سَلامَتِي فِي سَفَرِي هذَا بِهذَا.

Allāhumma innī urīdu safaran (kadhā wa kadhā) wa innī qad ishtaraytu salāmati fī safarī hādhā bi-hādhā.

O Allah, I intend to travel (such-and-such), and I have purchased my safety in this journey with this (recitation).

And give it (the charity) where it is appropriate, and when you return (from your journey), give charity in the same way as a token of gratitude.