The Holy Prophet of Islam (SAW) has said:

"Recite the Quran in such a way that your hearts develop a love for it and your skin becomes softened by it; but as soon as your hearts become indifferent to it (meaning that the Quran has no effect on you), then do not continue to recite it."

 Mustadrak al-Wasaail

Vol. 4,   Page 239.