It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Holy Prophet (peace and blessings be upon him) said: If a believing servant were to know the punishments that Allah has prepared, then no one would desire Paradise (they would only keep praying to be saved from Hell). And if a disbeliever were to realize the extent of Allah’s mercy, then no one would despair of Paradise. Allah has created one hundred mercies; He has placed one mercy in the hearts of His servants, by which they show mercy to one another, and the remaining ninety-nine mercies are with Allah.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10280