Anas reported that Allah's Messenger (ﷺ) established fraternity between Abu Ubaida bin Jarrah and Abu Talha.
Explanation & Benefits
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary: Benefits and Issues: The meaning of brotherhood or "mu’akhah" is to make them brothers so that they may become sympathetic and supportive to one another like real brothers, and so that they may become heirs to each other. In the era of ignorance (Jahiliyyah), this was called an alliance or friendship pact. Islam maintained this practice. However, when inheritance was made exclusive to relatives, then the aspect of inheritance was abrogated. But the aspect of sympathy (sharing in grief) and support and assistance was maintained. The statement "There is no alliance in Islam" (la hilfa fi’l-Islam) means that now, unlike in the era of ignorance, one cannot be made an heir like a blood brother on the basis of brotherhood. Inheritance will be distributed according to those principles which Islam has established.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 6462