In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Umm Salamah [radiyallaahu anhaa] said that the Messenger of Allaah [sallal-laahu-alayhi-wasallam] said: Indeed, ‘’I am only a human being and you people come to me with your disputes. And it may be that one of you can present his case more eloquently than the other and I consider him truthful, & judge in his favour. So, if I ever judge and give the right of a brother to his brother, then it is a piece of hell-fire & let him not take it.” [Bukhaari 7181]
Some Reminders From This Hadeeth
 The Ummah [i.e. the scholars and judges] have been commissioned to judge based on what is apparent; but the mere judgement of a judge cannot prohibit the lawful and allow the unlawful [i.e. because it cannot be taken if proven erroneous].
 This Hadeeth contains a refutation against those who say that the Messengers possess knowledge of the unseen.
 This hadeeth also shows that speech can be seen to be true based on what is apparent, but it is truly falsehood with regards to what is hidden within it.
 Also this hadeeth shows that the one who receives a judgement in his favour is more aware than every other person as to whether he is entitled to it or whether he is a falsifier. So, he takes it if he is entitled to it or leaves it if he a falsifier, because- in reality- a judgment cannot change an affair from what it was in origin [i.e. the original truth in the affair before its distortion or concealment].
 Also this hadeeth shows the sinfulness of the one who argues based on falsehood until he receives what he wants publicly, whilst he is upon falsehood.
 Also in this hadeeth is proof to show that a scholar can make a mistake and it is a refutation against those who say that every Mujtahid is correct.
 Also this hadeeth shows us that the Mujtahid is forgiven (when he makes a mistake).
Source: Excerpt from Saheeh Al-Bukhaari [ Kitaab Al-Ahkaam] with Fathul Baari. abridged & paraphrased