Hazrat Amr bin Al-Aas (may Allah be pleased with him) heard the Messenger of Allah (peace and blessings be upon him) say that when a ruler makes a decision based on his ijtihad (independent reasoning) and his decision is correct, he receives a double reward, and when he makes a decision based on ijtihad and makes a mistake, he receives a single reward.
Hadith Referenceاللؤلؤ والمرجان / كتاب الأقضية / 1118
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 96 كتاب الاعتصام: 21 باب أجر الحاكم إذا اجتهد فأصاب أو أخطأ»