Oppression leads to inevitable regret
Nahj al-Balāgha|Volume 1|Book 3|Chapter 186
١٨٦. وَقَالَ (عليه السلام): لِلظَّالِمِ الْبَادِي غَداً بِكَفِّهِ عَضَّةٌ.
186. Amīr al-mu’minīn, peace be upon him, said: He who takes the lead in oppression has to bite his hand (in repentance) tomorrow.