Sahih Muslim · Hadith 4696
The Book of Jihad and Expedition - كتاب الجهاد والسير
وحدثنا زهير بن حرب، حدثنا عبد الرحمن بن مهدي، عن شعبة، بهذا الإسناد وقال في حديثه فقال رسول الله صلى الله عليه وسلم " لقد حكمت فيهم بحكم الله " . وقال مرة " لقد حكمت بحكم الملك " .
Through the same chain of transmitters Shu'ba has narrated the same tradition in which he says that the Messenger of Allah (may peace be upon him) said (to Sa'd): You have adjudged according to the command of God. And once he said: you have adjudged by the decision of a king.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).