Ali on Zuhd: People who abandon part of Islam harm themselves

Abdullah ibn al-Hasan reported: Ali ibn Abi Talib, may Allah be pleased with him, said, “People do not abandon something from their religion, intending to benefit their worldly affairs, except that Allah will expose them to what is even more harmful and more evil for them.”

Source: al-Zuhd wal-Raqā’iq 2/11

عَنْ عَبْدِ اللَّهِ بْنِ الْحَسَنِ قَالَ قَالَ عَلِيّ بن أبي طالب رضي الله عنه لَا يَتْرُكُ النَّاسُ شَيْئًا مِنْ دِينِهِمْ إِرَادَةَ اسْتِصْلَاحِ دُنْيَاهُمْ إِلَّا فَتَحَ اللَّهُ عَلَيْهِمْ مَا هُوَ أَضَرُّ عَلَيْهِمْ وَمَا هُوَ شَرٌّ عَلَيْهِمْ مِنْهُ

2/11 الزهد والرقائق لابن المبارك