Instructions for Hasan, when returning from Siffin
Nahj al-Balāgha|Volume 1|Book 2|Chapter 31
وَاعْلَمْ أَنَّ الْإِعْجَابَ ضِدُّ الصَّوَابِ، وَآفَةُ الْأَلْبَابِ، فَاسْعَ فِي كَدْحِكَ، وَلَا تَكُنْ خَازِناً لِغَيْرِكَ، وَإِذَا أَنْتَ هُدِيتَ لِقَصْدِكَ فَكُنْ أَخْشَعَ مَا تَكُونُ لِرَبِّكَ.
Know that self-admiration is contrary to propriety (of action) and is a calamity for the mind. Therefore, increase your striving and do not become a treasurer for (wealth to be inherited by) others. When you have been guided on the right path humble yourself before Allāh as much as you can.