The Prophet ﷺ once passed by two graves, and those two persons (in the graves) were being tortured. He said, "They are being tortured not for a great thing (to avoid). One of them never saved himself from being soiled with his urine, while the other went about committing slander (to make enmity between friends). He then took a green leaf of a date-palm tree split it into two pieces and fixed one on each grave. The people said, "O Messenger of Allah ﷺ! Why have you done so?" He replied, "I hope that their punishment may be lessened till they (the leaf) become dry." (Using translation from Bukhārī 1361)
مَرَّ النَّبِيُّ ﷺ بِقَبْرَيْنِ فَقَالَ «إِنَّهُمَا لَيُعَذَّبَانِ وَمَا يُعَذَّبَانِ فِي كَبِيرٍ أَمَّا أَحَدُهُمَا فَكَانَ لَا يَسْتَتِرُ مِنْ بَوْلِهِ وَأَمَّا الْآخَرُ فَكَانَ يَمْشِي بِالنَّمِيمَةِ ثُمَّ أَخَذَ جَرِيدَةً رَطْبَةً فَشَقَّهَا نِصْفَيْنِ ثُمَّ غَرَزَ فِي كُلِّ قَبْرٍ وَاحِدَةً» فَقَالُوا يَا رَسُولَ اللهِ لِمَ صَنَعْتَ هَذَا قَالَ «لَعَلَّهُمَا أَنْ يُخَفَّفَ عَنْهُمَا مَا لَمْ يَيْبَسَا» قَالَ أَبُو عَبْدِ الرَّحْمَنِ بَعْضُ حُرُوفِ أَبِي مُعَاوِيَةَ لَمْ أَفْهَمْهُ كَمَا أَرَدْتُ