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. (Using translation from Muslim 2560a)
أَنَّ النَّبِيَّ ﷺ قَالَ «لَا يَحِلُّ لِمُسْلِمٍ أَنْ يَهْجُرَ أَخَاهُ فَوْقَ ثَلَاثٍ يَلْتَقِيَانِ فَيَصُدُّ هَذَا وَيَصُدُّ هَذَا وَخَيْرُهُمَا الَّذِي يَبْدَأُ بِالسَّلَامِ»