Sa'ad ibne-Abi Waqqas Radiyallahu 'anhu said that he heard Rasullullah Sallallahu 'alaihi wasallam saying: Indeed, this Qur'an has been revealed to create a deep grief and restlessness. So when you recite it, weep; and if you are unable to weep, then make a weeping face. And recite it with a pleasing voice, as one who does not (try to) recite with a pleasant voice is not from us. (Ibne-Majah: 1337)
Note: Some scholars have also given another interpretation to this
Hadith; that the one who does not become contented and free from want of
what others have, by the blessing of the Qur'an, in fact has not
properly benefitted from it and hence is not from us.