Hadith 5036
وَعَن أبي خرَاش السُّلَميَّ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «مَنْ هَجَرَ أَخَاهُ سَنَةً فَهُوَ كسفك دَمه» . رَوَاهُ أَبُو دَاوُد
Abu Khirash Salmi (may Allah be pleased with him) reports that he heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever severs contact with his brother for a whole year, it is as if he has shed his blood." Hasan, narrated by Abu Dawood.