Is it a sound action for a Muslim to defend his Muslim brother who is exposed to danger, even if that leads to his own harm?

A Muslim is the brother of a Muslim. It is not permissible to hand him over to an enemy or to abandon him in times of need if assistance is possible. Selflessly enduring harm for the sake of others is a virtue, and it is commendable in Islamic law, and its doer is naturally praised. It is permissible for a Muslim, rather it is recommended, to defend his Muslim brother even if he incurs harm. However, one should not expose himself to what he cannot bear, as the Prophet, peace and blessings be upon him, said: "It is not befitting for a believer to humiliate himself." They asked: "How does he humiliate himself?" He replied: "By exposing himself to trials that he cannot endure."