Holding Fast to the Qur'an and Sunnah

Bukhari :: Book 9 :: Volume 92 :: Hadith 450

Narrated 'Amr bin Al-'As:

That he heard Allah's Apostle saying, "If a judge gives a verdict according to the best of his knowledge and his verdict is correct (i.e. agrees with Allah and His Apostle's verdict) he will receive a double reward, and if he gives a verdict according to the best of his knowledge and his verdict is wrong, (i.e. against that of Allah and His Apostle) even then he will get a reward ."