Ibn Umar may Allah bless him reported:
Messenger of Allah peace be upon him said: "A Muslim is a brother of another Muslim. So he should not oppress him nor should he hand him over to (his satan or to his self which is inclined to evil). Whoever fulfills the needs of his brother, Allah will fulfill his needs; whoever removes the troubles of his brother, Allah will remove one of his troubles on the Day of Resurrection; and whoever covers up the fault of a Muslim, Allah will cover up his fault on the Day of Resurrection".
Commentary: A Muslim is a brother of another. It is haram for Muslims to oppress one another. Not only a Muslim should not oppress the other, but also he should not leave him without help. If a Muslim is persecuted for some reason, his Muslim brother must do his best to rescue.
One of the virtues of a Muslim is to fulfill the needs of his Muslim brother. The reward for this quality has already been mentioned above. The needs of the one who bestows his brother's needs come from Allah.
A Muslim also tries his best to care for his brother. Because he follows this hadith and believes that Allah will take care of the one who takes care of his brother.