Kitāb al-Muʾmin
Hadith 176176 - وقال النبي صلى الله عليه وآله وسلم: من لا يعرف لأخيه مثل ما يعرف له فليس بأخيه.
176. The Prophet (a.s) has said: One who does not care to know of his brother what he knows of him is not his brother.