Praise be to God; whose compassion is all-embracing and Whose mercy is universal; Who rewards His servants for their remembrance [dhikr] [of Him] with His remembrance [of them] - verily God (Exalted is He!) has said, 'Remember Me, and I will remember you' - Opening lines from Kitab al-Adhkar wa'l Da'awat of the Ihya ulum ad-Din
Al-Ghazali