He owed a debt by 'Abdullah bin Abi Hadrad Al-Aslami. He met him, and asked him to pay it off. They exchanged words until their voices became loud. The Messenger of Allah [SAW] passed by them and said: "O Ka'b!" and he gestured with his hand to say half. So he took half of what was owed and let him off the other half.  

أَنَّهُ كَانَ لَهُ عَلَى عَبْدِ اللَّهِ بْنِ أَبِي حَدْرَدٍ الأَسْلَمِيِّ يَعْنِي دَيْنًا فَلَقِيَهُ فَلَزِمَهُ فَتَكَلَّمَا حَتَّى ارْتَفَعَتِ الأَصْوَاتُ فَمَرَّ بِهِمَا رَسُولُ اللَّهِ ﷺ فَقَالَ يَا كَعْبُ فَأَشَارَ بِيَدِهِ كَأَنَّهُ يَقُولُ النِّصْفَ فَأَخَذَ نِصْفًا مِمَّا عَلَيْهِ وَتَرَكَ نِصْفًا