I heard him say that two disputants brought their case before Amr bin As, and he gave judgment between them. The one against whom the judgment was given was displeased, so he went to the Messenger of Allah ﷺ and informed him.The Messenger of Allah ﷺ said, "When a judge gives a ruling, exerting his judgment and gets it right, he receives ten rewards. And when he exerts his judgment but errs, he still receives one reward, or two."
حدثنا حسن حدثنا ابن لهيعة حدثنا الحارث بن يزيد عن سلمة بن أكسوم قال سمعت ابن حجيرة يسأل القاسم بن البرحي كيف سمعت
سمعته يقول إن خصمين اختصما إلى عمرو بن العاصي فقضى بينهما فسخط المقضي عليه فأتى رسول الله ﷺ فأخبره فقال رسول الله ﷺ إذا قضى القاضي فاجتهد فأصاب فله عشرة أجور وإذا اجتهد فأخطأ كان له أجر أو أجران