Sahih al-Bukhari Book 46, Hadith 6
I heard Al-Bara' bin `Azib saying, "The Prophet (ﷺ) orders us to do seven things and prohibited us from
doing seven other things." Then Al-Bara' mentioned the following:--
(1) To pay a visit to the sick (inquiring about his health),
(2) to follow funeral processions,
(3) to say to a sneezer, "May Allah be merciful to you" (if he says, "Praise be to Allah!"),
(4) to return greetings,
(5) to help the oppressed,
(6) to accept invitations,
(7) to help others to fulfill their oaths. (See Hadith No. 753, Vol. 7)
Allah's Messenger (ﷺ) said, "Help your brother, whether he is an oppressor or he is an oppressed one. People asked, "O Allah's Messenger (ﷺ)! It is all right to help him if he is oppressed, but how should we help him if he is an oppressor?" The Prophet (ﷺ) said, "By preventing him from oppressing others."
The Prophet (ﷺ) said, "A believer to another believer is like a building whose different parts enforce each other." The Prophet (ﷺ) then clasped his hands with the fingers interlaced (while saying that).