Imam al-Sadiq (AS) said, ‘Every single good deed that the servant carries out has a reward mentioned for it in the Quran except for the night prayer, for verily Allah has not expressed its reward because of the great significance it holds with Him. Thus, He says, “Their sides vacate their beds to supplicate their Lord in fear and hope …No one knows what has been kept hidden for them of comfort as a reward for what they used to do” (Qur'an 32:16)