The Messenger of Allah ﷺ said, "Every sin of the martyr is forgiven except debt."
أن رسول الله ﷺ قال: يغفر للشهيد كل ذنب إلا الدين.
Muslim narrated it in the Book of Emirate (1886:119), from Zakariya bin Yahya bin Salih Misri, who said, "Mufaddal bin Fadala narrated to us," from Ayyash bin Abbas Qutbani, from Abdullah bin Yazid Abu Abdul-Rahman Hubli, from Abdullah bin Amr bin As, and he mentioned it.