ভূমিকা
"Verily We have sent down the Book to you with that you may judge between people by what Allah has shown (taught) you. And be not an advocate for the treacherous." Basing on what is recorded in some authentic commentary books, once it happened that, in one of the battles, a Muslim stole a chain mail. When he was going to be marked by ignominy, he threw the chain mail into the house of a Jew, and then gathered some men saying that the Jewish person was a thief, not that Muslim.
The subject was brought to the Prophet (S) and the verse was revealed, announcing such: "Verily We have sent down the Book to you with the Truth that you may judge between people by what Allah has shown (taught) you..." In this verse, at first Allah recommends the Prophet (S) that the purpose of sending down this heavenly Book is that these rules of the truth and equity should be practiced among people.
It says: "Verily We have sent down the Book to you with the Truth that you may judge between people by what Allah has shown (taught) you. ..." Then, it awares the Prophet (S) by saying that: "... And be not an advocate for the treacherous." It is cited in Majma'-ul-Bayan (vol. 6, p.
32 Persian translation) that although this verse addresses the Prophet (S), the target is the Ummat of the Prophet (S) not the Prophet himself, because, upon the consensus of Ummat, the Prophet (S) is immaculate from all sins and disgraces. Therefore, since the revelation of the Qur'an is based on the truth, the judgements should be performed upon the basis of the truth, too, not upon the relations.