Sunan Ibn Majah, Volume 3, Book 21, Hadith 2619 (DarusSalam) ⓘ
It was narrated from Bara' bin Azib that the Messenger of Allah said: “If this world were to be destroyed, that would be less significant before Allah (SWT) than the unlawful killing of a believer.”
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا مَرْوَانُ بْنُ جَنَاحٍ، عَنْ أَبِي الْجَهْمِ الْجُوزَجَانِيِّ، عَنِ الْبَرَاءِ بْنِ عَازِبٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لَزَوَالُ الدُّنْيَا أَهْوَنُ عَلَى اللَّهِ مِنْ قَتْلِ مُؤْمِنٍ بِغَيْرِ حَقٍّ " .
also referenced under: Hadith 2619 (Reference) & Book 21, Hadith 2717 (In-Book)