Al-Kāfi - Volume 1 > Chapter on Those who use their Knowledge to Fill their Stomach and are Boastful for it
Hadith #1

1ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى وَعَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ جَمِيعاً عَنْ حَمَّادِ بْنِ عِيسَى عَنْ عُمَرَ بْنِ أُذَيْنَةَ عَنْ أَبَانِ بْنِ أَبِي عَيَّاشٍ عَنْ سُلَيْمِ بْنِ قَيْسٍ قَالَ سَمِعْتُ أَمِيرَ الْمُؤْمِنِينَ (عَلَيْهِ السَّلام) يَقُولُ قَالَ رَسُولُ الله (صَلَّى اللهُ عَلَيْهِ وَآلِه) مَنْهُومَانِ لا يَشْبَعَانِ طَالِبُ دُنْيَا وَطَالِبُ عِلْمٍ فَمَنِ اقْتَصَرَ مِنَ الدُّنْيَا عَلَى مَا أَحَلَّ الله لَهُ سَلِمَ وَمَنْ تَنَاوَلَهَا مِنْ غَيْرِ حِلِّهَا هَلَكَ إِلا أَنْ يَتُوبَ أَوْ يُرَاجِعَ وَمَنْ أَخَذَ الْعِلْمَ مِنْ أَهْلِهِ وَعَمِلَ بِعِلْمِهِ نَجَا وَمَنْ أَرَادَ بِهِ الدُّنْيَا فَهِيَ حَظُّهُ.

1. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa and Ali ibn Ibrahim from his father, both of them from Hammad ibn ‘Isa from ‘Umar ibn ’Udhayna from Aban ibn abu ‘Ayyash from Sulaym ibn Qays who has said the following. “(Imam) Ali (a.s.) narrated from the holy Prophet who said, ‘Two kinds of people with great appetites do not become satisfied. A person of great appetite for the worldly gains and a person with great appetite for knowledge. In the matters of the worldly gains if one would limit himself to what Allah has made lawful form him he is saved and if one would accumulate such gains in unlawful ways he is destroyed unless he repents and changes his ways. In the matters of knowledge if one would acquire it from the people of knowledge and practice accordingly he is saved and if one would use it for the worldly gains then that is what one gets.’”