Abu Darda on Ego: One who follows his ego harms himself

Hasan reported: Abu Darda, may Allah be pleased with him, said, “Whoever follows his ego in regards to everything he sees in people, then his sadness will be lengthened and his rage will not be healed.”

Source: al-Mudārāh al-Nās 27

عَنِ الْحَسَنِ قَالَ قَالَ أَبُو الدَّرْدَاءِ رضي الله عنه مَنْ يُتْبِعْ نَفْسَهُ كُلَّ مَا يَرَى فِي النَّاسِ يَطُلْ حُزْنُهُ وَلَا يَشْفِ غَيْظَهُ

27 مداراة الناس لابن أبي الدنيا