In the name of Allah, the Most Gracious, the Most Merciful.
Book of Judiciary (Kitab al-Qada')
The foundation for judiciary and its legitimacy are the Book (Qur'an), the Sunnah, and consensus (Ijma'). As for the Book, there is the saying of Allah the Almighty: "O David, indeed We have made you a successor upon the earth, so judge between the people in truth and do not follow [your own] desire, as it will lead you astray from the way of Allah" (Surah Sad: 26). Also, the saying of Allah the Almighty: "And judge between them by what Allah has revealed" (Surah al-Ma'idah: 46), and His saying: "But when they are called to Allah and His Messenger to judge between them" (Surah al-Nur: 48), and His saying: "But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then do not find within themselves discomfort from what you have judged and submit in [full, willing] submission" (Surah al-Nisa': 65). As for the Sunnah, there is what 'Amr ibn al-'As narrated from the Prophet, peace and blessings of Allah be upon him, that he said: "If a judge exerts his effort (ijtihad) and hits the mark, he has two rewards, and if he exerts his effort and makes a mistake, he has one reward" (agreed upon).
There are many other verses and reports besides these. The Muslims have reached consensus on the legitimacy of establishing the judiciary and judging between people.
Section: The judiciary is a collective obligation (fard kifayah) because the affairs of the people cannot remain in order without it. Thus, it was an obligation upon them, like Jihad and the Imamate. Ahmad said: "People must have a ruler, or else the rights of the people will be lost!"
(1) Surah Sad: 26. (2) Surah al-Ma'idah: 46. (3) Surah al-Nur: 48. (4) Surah al-Nisa': 65. (5) In the original and in [B]: "and makes a mistake". (6) Recorded by al-Bukhari in the chapter: "The reward of the judge if he exerts effort and is correct or mistaken," from the Book of Holding Fast to the Qur'an and Sunnah (Sahih al-Bukhari 9/133); and by Muslim in the chapter: "Clarification of the reward of the judge if he exerts effort and is correct or mistaken," from the Book of Judicial Decisions (Sahih Muslim 3/1342). It was also recorded by Abu Dawud in the chapter: "On the judge who errs," from the Book of Judicial Decisions (Sunan Abi Dawud 2/268); by Ibn Majah in the chapter: "The judge who exerts effort and hits the truth," from the Book of Judgments (Sunan Ibn Majah 2/776); and by Imam Ahmad in the Musnad (2/187, 4/198, 204).
