In The Name of Allah, The Most Merciful, The Bestower of Mercy.

It is obligated to a Muslim to uphold justice and to bear witness against himself that he has fallen into falsehood when he falls into falsehood, that he is upon error when he errs, or that he has committed injustice when he commits injustice. He bears witness against himself that he has erred, opposed the truth, and announces that without shame. Otherwise, he may be from those who betray Allah, those distanced from upholding justice for Allah, Lord of the Aalameen. Similarly, if his son, brother, or father is in the wrong, he must clarify their mistakes, for this is religion ordained by Allah, not based on personal whims.

Majmu 14/476