What is the ruling on my silence regarding the 'Urfi marriage of my chaste sister to a man she became pregnant by out of wedlock, knowing that my paternal uncle is her guardian and approves of this marriage, and must I annul this marriage and clash with my family, or is it sufficient for me to disapprove and distance myself?

The aforementioned marriage is invalid because its pillars are not complete, specifically the صيغة (declaration) and the ولي (guardian), and also because the woman is pregnant. Furthermore, this marriage is not lawful. Therefore, it is not permissible to remain silent about it, and the uncle and sister must be advised. If they do not respond, the matter should be referred to the competent authorities.