Amr b. al-'As reported that he heard Allah's Messenger (ﷺ) as saying:When a judge gives a decision, having tried his best to decide correctly and is right, there are two rewards for him; and if he gave a judgment after having tried his best (to arrive at a correct decision) but erred, there is one reward for him

This hadith has been narrated on the authority of Abu Huraira with another chain of transmitters

This hadith has been transmitted on the authority of Usama b. al-Had al-Laithi