ENOfficial
It is unlawful for a believer to sever relations with his brother for more than three days.
Source: sunnah.com
Other translations
Arabic
لَا یَحِلُّ لِمُؤمِنٍ اَنْ یَّجُهْرَ أخَاهُ فَوقَ ثَلَاثَةِ أیَّامٍ
sunnah.com
Collections of Forty
Book 3Hadith Number 11