To make the Heart Tender (Ar-Riqaq)
Bukhari :: Book 8 :: Volume 76 :: Hadith 573
Narrated Abu Huraira:
The Prophet said, "None will enter Paradise but will be shown the place he would have occupied in the (Hell) Fire if he had rejected faith, so that he may be more thankful; and none will enter the (Hell) Fire but will be shown the place he would have occupied in Paradise if he had faith, so that may be a cause of sorrow for him."