Mishkat al-Masabih 9 Supplications كتاب الدعوات 139

وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَوْ يَعْلَمُ الْمُؤْمِنُ مَا عِنْدَ اللَّهِ مِنَ الْعُقُوبَةِ مَا طَمِعَ بِجَنَّتِهِ أَحَدٌ وَلَوْ يُعْلَمُ الْكَافِرُ مَا عِنْدَ اللَّهِ مِنَ الرَّحْمَةِ مَا قَنَطَ من جنته أحد»

Abu Huraira reported God’s messenger as saying, “If the believer knew the punishment God has prepared, no one would hope for His paradise; and if the infidel knew the extent of His mercy, no one would despair of attaining His paradise.” (Bukhari and Muslim.)