It is narrated from Sayyiduna al-Nawwas bin Sim'an al-Kilabi (may Allah be pleased with him) that he said: I heard the Messenger of Allah (peace and blessings be upon him) saying: "There is no heart except that it is between two of the fingers of the Most Merciful; if He wills, He keeps it upright (upon guidance), and if He wills, He causes it to deviate (toward misguidance)." And the Messenger of Allah (peace and blessings be upon him) used to supplicate: 'Allahumma ya muqallib al-qulub, thabbit qulubana 'ala dinik' (O Allah, O Turner of hearts, keep our hearts firm upon Your religion). And the Scale is in the hand of the Most Merciful; He raises some peoples and lowers others until the Day of Resurrection. This hadith is sahih (authentic) on the condition of Imam Muslim.