Hadith
The Holy Prophet (pbuh) said:
 يحِجُّ أغنِياءُ أُمّتي لِلنَّزهَةِ ويحِجُّ أَوسَاطُها لِلتّجارَةِ ويحِجُّ فُقَراؤُهُم لِلرّياءِ والسُّمعَةِ، فعِندَها يكُونُ أَقوامٌ يَتَعلّمُونَ القُرآنَ لِغيرِ اللهِ ويَتّخِذُونهُ مَزامِيرَ، ويكونُ أَقوامٌ يَتفقَّهونَ لِغيرِ اللهِ.
The rich will go to Mecca for amusement, the middle-class for business, and the poor for showing off and fame. At that time, people will learn the Holy Quran for purposes other than Allah, recite it as song, and engage in learning (Islamic) jurisprudence for worldly benefits.
See Tafsir al-Mizan; vol. 5 p.434 (as quoted from Tafsir al-Qummi)