1. If one knows of someone who is being oppressed or undergoing some difficulty and one is in the position to assist the person and remove the oppression, then one should do so. However, if one is unable to do so, then one should advise the person to go to someone who will be able to assist him. Similarly, one should make dua for the person.
عن أنس رضي الله عنه، قال: قال رسول الله صلى الله عليه وسلم: انصر أخاك ظالما أو مظلوما فقال رجل: يا رسول الله، أنصره إذا كان مظلوما، أفرأيت إذا كان ظالما كيف أنصره؟ قال: تحجزه، أو تمنعه، من الظلم فإن ذلك نصره (صحيح البخاري، الرقم: 2443)
Hazrat Anas (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “Help your brother, whether he is an oppressor or oppressed.” A person asked, “O Rasulullah (sallallahu ‘alaihi wasallam)! I will assist him (my brother) in the case where he is oppressed. However, how can I assist him in the case where he is an oppressor?” Rasulullah (sallallahu ‘alaihi wasallam) said, “Stop him or prevent him from his oppression, as this will be the way for you to assist him.”
وعن ابن عمر أن رسول الله صلى الله عليه وسلم قال: المسلم أخو المسلم لا يظلمه ولا يسلمه ومن كان في حاجة أخيه كان الله في حاجته ومن فرج عن مسلم كربة فرج الله عنه كربة من كربات يوم القيامة ومن ستر مسلما ستره الله يوم القيامة (صحيح البخاري، الرقم: 2442)
Hazrat ibnu Umar (radhiyallahu ‘anhuma) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “A Muslim is the brother of his fellow Muslim. He will thus neither oppress him nor forsake and abandon him. Whoever sees to the need of his Muslim brother, Allah Ta‘ala will fulfil his need and whoever relieves his Muslim brother of some difficulty, Allah Ta‘ala, in lieu of this, will relieve him of a great difficulty from the difficulties of the Day of Qiyaamah. Whoever conceals the fault (and sin) of his Muslim brother, Allah Ta‘ala will conceal his faults (and sins) on the Day of Qiyaamah.”