سنن أبي داود

It was narrated that `Amr bin Al-`As said "The Messenger of Allah (ﷺ) said: 'If a judge passes a judgment having exerted himself to arrive at what is correct, and he is indeed correct, he will have two rewards. If he passes judgment having exerted himself to arrive at what is correct, but it is incorrect, he will have one reward.'"

I narrated it to Abu Bakr bin Hazm and he said: "This is what Abu Salamah narrated to me from Abu Hurairah.