Sahih al-Bukhari Book 46, Hadith 8
The Prophet (ﷺ) said, "Oppression will be a darkness on the Day of Resurrection."
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).
The Prophet (ﷺ) sent Mu`adh to Yemen and said, "Be afraid, from the curse of the oppressed as there is no screen between his invocation and Allah."