In Surah Aal ‘Imran, Allah subhanahu wa ta’ala says,
يَوْمَ تَجِدُ كُلُّ نَفْسٍ مَّا عَمِلَتْ مِنْ خَيْرٍ مُّحْضَرًا وَمَا عَمِلَتْ مِن سُوءٍ تَوَدُّ لَوْ أَنَّ بَيْنَهَا وَبَيْنَهُ أَمَدًا بَعِيدًا ۗ وَيُحَذِّرُكُمُ اللَّهُ نَفْسَهُ ۗ وَاللَّهُ رَءُوفٌ بِالْعِبَادِ
“On the Day when every person will find all the good he has done, and all the evil he has done he will wish that there were a great distance between him and his evil. And Allah warns you against Himself and Allah is full of Kindness to the (His) slaves.” [v. 30]
Ra’fah (‘kindness’) is more intense than Mercy and it is also more specific to the believers hence why it only appears a handful of times in the Qur’an unlike ‘Rahma’.
But interestingly, they say that in this verse, Allah `azza wa jall ends with وَيُحَذِّرُكُمُ اللَّهُ نَفْسَهُ ۗ وَاللَّهُ رَءُوفٌ بِالْعِبَادِ to show that from His Kindness is that He warns the slave of Himself so that he can work righteousness in this world and avoid punishable sin. This is because on the Day that matters the most, every person will find their deeds before them. So He Who warns of danger ahead of time has indeed been kind to you. Were it not for the warning, you would never know what lies ahead…
– Info taken from Asrar al-Tikrar fil-Qur’an, by Taj al-Deen al-Karmani