Sunan an-Nasa'i, Book 37, Hadith 128 (In-Book) ⓘ
It was narrated that Abu Ja'far said: "The Messenger of Allah [SAW] said: 'Whoever is killed defending his wealth and is killed unjustly, he is a martyr.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَلْقَمَةَ، عَنْ أَبِي جَعْفَرٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ قُتِلَ دُونَ مَظْلَمَتِهِ فَهُوَ شَهِيدٌ " . قَالَ أَبُو عَبْدِ الرَّحْمَنِ حَدِيثُ الْمُؤَمَّلِ خَطَأٌ وَالصَّوَابُ حَدِيثُ عَبْدِ الرَّحْمَنِ .
also referenced under: Hadith 4093 (Reference) & Volume 5, Book 37, Hadith 4098 (DarusSalam)