Imam Ali (AS) said, Be cautious not to consider the sin of others as great while you deem it to be small [when it comes] from yourself, or to consider your worship as abundant while you deem the same to be less when performed by others.
الإمامُ عليٌّ (عَلَيهِ الّسَلامُ) : إيّاكَ أنْ تَسْتَكْبِرَ مِنْ مَعْصِيَةِ غَيْرِكَ ما تَسْتَصْغِرُهُ مِنْ نَفْسِكَ أو تَسْتَكْثِرَ مِنْ طاعَتِكَ ما تَسْتَقِلُّهُ مِنْ غَيْرِكَ