He has opened for you the door of repentance; therefore, whenever you call Him, He hears your call, and whenever you whisper to Him, He knows the whisper. Place before Him your needs, unveil yourself before Him, complain to Him of your worries, beseech Him to remove your troubles, seek His help in your affairs, and ask from the treasuries of His mercy that which no one else has power to give, namely length of life, health of body, and increase in sustenance. He has placed the keys of His treasuries in your hands in the sense that He has shown you the way to ask Him. Therefore, wherever you wish, open the doors of His favour with prayer, and let abundant rains of His mercy fall on you.
— Imam Ali (a), Nahj al-Balagha, Letter 31