(8) باب تَحْرِيمِ الْهَجْرِ فَوْقَ ثَلاَثٍ بِلاَ عُذْرٍ شَرْعِيٍّ
Abu Ayyub Ansiri reported Allah's Messenger (ﷺ) as saying:
It is not permissible for a Muslim to have estranged relations with his brother beyond three nights, the one turning one way and the other turning the other way when they meet; the better of the two is one who is the first to give a greeting.
Reference: Sahih Muslim 2560 a
In-book reference: Book 45, Hadith 31
USC-MSA web (English) reference(deprecated numbering scheme): Book 32, Hadith 6210