What is the ruling on a righteous man proposing to a woman who has already been proposed to by a wicked man?

The Shaykh : Yes, indeed. As you said, the majority of scholars hold that it is not permissible, because he is a brother, despite his wickedness. Some scholars said it is permissible, but what appears from the hadith is that it is not permissible. However, he can save the woman, as the brother 'Abd al-Rahman mentioned, by sending a message to her saying, "This man who proposed to you is such-and-such, so leave him, and Allah will provide you with a way out." Then, if she leaves him, he may come forward and propose to her.