Musnad Ahmad 1007:69

Hajjaj narrated to us, Laith narrated to us, Sa’id ibn Abi Sa’id narrated to me, from Abdullah ibn Abi Qatadah, that he heard Abu Qatadah narrating from the Messenger of Allah (peace and blessings of Allah be upon him) that he stood among them and mentioned to them that Jihad in the way of Allah and belief in Allah are the best of deeds. A man stood up and said: "O Messenger of Allah, do you see that if I am killed in the way of Allah, my sins will be expiated for me?" The Messenger of Allah (peace and blessings of Allah be upon him) said to him: "Yes, if you are killed in the way of Allah, while you are patient, seeking reward, advancing, and not retreating." Then the Messenger of Allah (peace and blessings of Allah be upon him) said: "What did you say?" He said: "Do you see that if I am killed in the way of Allah, my sins will be expiated for me?" The Messenger of Allah (peace and blessings of Allah be upon him) said: "Yes, if you are killed while you are patient, seeking reward, advancing, and not retreating—except for debt, for Jibril said that to me."