The Messenger of Allah (SAW) said; Three supplications will not be rejected (by Allah (SWT)), the supplication of the parent for his child, the supplication of the one who is fasting, and the supplication of the traveler. [al-Bayhaqi, at-Tirmidhi – Sahih]
During travel supplication is heard by Allah (SWT) if the trip is for a good reason, but if the trip is for a bad intention or to perform illegal things (making sins) this will not apply to it.
In another hadith; The Prophet (SAW) declared: ‘Three du’as are surely answered: The du’a of the oppressed, the du’a of the traveler, and the du’a of the father/mother (upon their child)‘. The One who is suffering injustice is heard by Allah (SWT) when he invokes Allah (SWT) to retain his rights from the unjust one or oppressor. Allah (SWT) has sworn to help the one who is suffering from injustice sooner or later as the Messenger of Allah (SAW) said.
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