Sayyiduna Abu Huraira, may Allah be pleased with him, narrates this statement of the Prophet Muhammad, peace and blessings be upon him: "If a believer were to know what kind of punishment exists with Allah Almighty, then no one would hope for Paradise; and if a disbeliever were to know how great Allah Almighty's mercy is, then no one would despair of Paradise."
Hadith Referenceصحیح ابن حبان / كتاب البر والإحسان / 345
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «الصحيحة» (1634): ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده جيد على شرط مسلم.