Understanding Ijtihad and Legal Differences
Is A Mujtahid Sinful For an Incorrect Opinion?
No, there is no sin if a mujtahid imam is incorrect in his judgment. Rather there is reward, since he did his utmost to arrive at the ruling. This is based on the explicit hadith that states a mujtahid receives 2 rewards if he is correct and 1 reward if incorrect. [Bukhari, Muslim]