All the sins of a Shahid (martyr) are forgiven except debt.
Sahih Muslim Book 33, Hadith 179
← Previous Hadith " A man came to the Messenger of Allah (ﷺ) and he was sitting on the pulpit.... He said: What do you find if I strike with the sword?" (The rest of the tradition is the same as the previous one.)

Sahih Muslim Book 33, Hadith 178 Next Hadith → Death in the way of Allah blots out everything except debt.

Sahih Muslim Book 33, Hadith 180