عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو إِنَّ خَصْمَيْنِ اخْتَصَمَا إِلَى عَمْرِو بْنِ الْعَاصِ فَقَضَى بَيْنَهُمَا، فَسَخِطَ الْمَقْضِيُّ عَلَيْهِ فَأَتَى رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ فَأَخْبَرَهُ، فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((إِذَا قَضَى الْقَاضِي فَاجْتَهَدَ فَأَصَابَ فَلَهُ عَشَرَةُ أُجُورٍ، وَإِذَا اجْتَهَدَ فَأَخْطَأَ كَانَ لَهُ أَجْرٌ أَوْ أَجْرَانِ))
It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that two men brought their case to Sayyiduna Amr bin Aas (may Allah be pleased with him). He judged between them, and the one against whom the decision was made became upset and went to the Messenger of Allah (peace and blessings be upon him) and complained. The Prophet (peace and blessings be upon him) said to him: When a judge gives a verdict and strives with full effort and makes the correct decision, he receives ten rewards, and if he makes a mistake despite his full effort, he still receives one or two rewards.