Sahih Muslim – Hadith No : 4696

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.

Hadith In Arabic Text :

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 ‏”‏ ‏.‏

Chapter : The Book of Jihad and Expedition – كتاب الجهاد والسير