Abu Hurairah reported,
The Messenger of Allah ﷺ stood addressing the people and mentioned that faith in Allah and striving in the path of Allah are among the best deeds in Allah's sight.A man stood up and asked, "Messenger of Allah, tell me, if I am killed in the path of Allah while patient, seeking reward, advancing and not retreating, will Allah wipe away my sins?"He replied, "Yes."The man said, "What did you say?"The Prophet ﷺ repeated his answer just as he had said it, "Yes."The man asked again, "What did you say?"The Prophet ﷺ repeated the answer once more.The man said, "Messenger of Allah, tell me, if I am killed in the path of Allah, patient, seeking reward, advancing and not retreating, will Allah wipe away my sins?"He replied, "Yes, except for debt, for Jibreel 
whispered that to me."
Ahmad 8075
Sahihحدثنا محمد بن بكر حدثنا عبد الحميد بن جعفر الأنصاري أخبرني عياض بن عبد الله بن أبي سرح
عن أبي هريرة قال
قام رسول الله ﷺ يخطب الناس فذكر الإيمان بالله والجهاد في سبيل الله من أفضل الأعمال عند الله قال فقام رجل فقال يا رسول الله أرأيت إن قتلت في سبيل الله وأنا صابر محتسب مقبلا غير مدبر كفر الله عني خطاياي قال نعم قال فكيف قلت قال فرد عليه القول كما قال قال نعم قال فكيف قلت قال فرد عليه القول أيضا قال يا رسول الله أرأيت إن قتلت في سبيل الله صابرا محتسبا مقبلا غير مدبر كفر الله عني خطاياي قال نعم إلا الدين فإن جبريل عليه السلام سارني بذلك
Its isnad is sahih. Iyad bin Abdullah bin Saad bin Abu Sarh, the Qurayshi, the Amiri, was a trustworthy successor, deemed reliable by Ibn Main, Nasai, and others. Bukhari wrote about him in al-Kabir 1/4:21, as did Ibn Saad 5:180 and Ibn Abu Hatim 3/1/408, and Musab mentioned him in Nasab Quraysh, page 433, saying that he met the companions of the Prophet ﷺ.This hadith will come again at 8353 through Uthman bin Umar, from Abdul-Hameed bin Jafar, with this same isnad, and it appears in Jami al-Masanid wal-Sunan 7:218 from both places. Haythami mentioned it in Majma al-Zawaid 4:128, saying, Ahmad narrated it, and its men are the men of the Sahih. However, its text there appears abridged, with the repetition of the question and answer omitted. I consider it more likely that this is an error on the part of a copyist or printer.The meaning of this hadith, in a similar context, is also established through the hadith of Abu Qatada, narrated by Muslim 2:97-98, Tirmidhi 3:35-36, Nasai 2:62, and Darimi 2:207. It will also come in the Musnad 5:303-304, 308, Halabi edition. See also what has already passed in the Musnad of Abdullah bin Amr, 7151.