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 Imarah (1886) from Zakariya bin Yahya bin Salih Misri, who said, Mufaddal, meaning Ibn Fadala, narrated to us, from Ayyash, who is Ibn Abbas Qatbani, from Abdullah bin Yazid Abu Abdul-Rahman Hubli, from Abdullah bin Amr bin As, and he related it.