He heard the Messenger of Allah ﷺ say, "When a judge gives a ruling and exercises his best judgment and then arrives at the right decision, he receives two rewards. When he gives a ruling and exercises his best judgment and then errs, he receives one reward."This is the narration of Abdul-Aziz bin Muhammad, with both chains of transmission together.
و حدثني عبد الله بن عبد الرحمن الدارمي أخبرنا مروان يعني ابن محمد الدمشقي حدثنا الليث بن سعد حدثني يزيد بن عبد الله بن أسامة بن الهاد الليثي بهذا الحديث مثل رواية عبد العزيز بن محمد بالإسنادين جميعا