“(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.’”