Sayyiduna Nu'aym bin Hammar al-Ghatafani (may Allah be pleased with him) narrates: I heard the Prophet (peace and blessings be upon him) say: "The heart of every human being is between two of the fingers of the Most Merciful. If Allah Almighty wishes to make it deviate, He makes it deviate, and if He wishes to keep it upright, He keeps it upright. Every day the Scale is in the Hand of Allah Almighty; He raises some peoples and lowers others, and so it will be until the Day of Resurrection."
Al-Tabarani recorded it, and its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب القدر / 11914