Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Sa’d bin Abi Waqqas (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: “Fighting with a believer is disbelief, and abusing him is wickedness, and it is not permissible for any Muslim to sever relations with his brother for more than three days (due to breaking ties of kinship).”