‘Abdullāh ibn ‘Amr ibn al-‘Ās (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Allah forgives everything for the martyr except the debt." Another narration for him reads: "Fighting in the cause of Allah expiates everything except the debt.”
Martyrdom expiates all sins, the minor and the major thereof, except for the debt. Martyrdom does not expiate the debt, and that is due to the greatness of the rights of people, especially those related to properties, which indeed, are the dearest to them. The same applies to anything pertaining to people's rights; such as theft, usurpation, and treachery. Fighting in the cause of Allah, martyrdom, and other acts of righteousness do not expiate transgression against people's rights, rather, they only expiate neglect of the rights of Allah, the Exalted.