Marriage by exchange is not permissible

This is a letter received from Yahya ibn Ali Muhammad Jad Allah al-Yamani, residing in al-Aflaj in al-Hadar. He says in his letter: I am married by exchange to my sister, but my sister’s husband paid the mahr, and I also paid the mahr for my wife. This contract was completed with the consent of both wives, and each one is satisfied with her husband. Is this contract valid or not? Please inform us; may Allah reward you.
Answer: Marriage by exchange is not permissible, and it is called marriage by shighar. The Prophet (peace and blessings be upon him) prohibited it in many hadiths, narrated by Jabir, Abu Hurayrah, Ibn Umar, and others. It is obligatory for the believer to beware of this marriage and not to do it. If he does it, let him repent to Allah, seek Allah’s forgiveness, and renew the marriage, for it is a defective marriage. He should avoid it until he renews the marriage. If he desires her and she desires him, he should renew the marriage without the condition of the other woman. He should renew the marriage with her guardian over her with a new mahr, even if it is immediate; there is no need for a waiting period, because the water is his, if she wants him and he wants her. He renews the marriage without the condition of the other woman. As for if she does not want him, he divorces her with one divorce and separates from her, because he married her without right.
And so the other, his partner, renews it with a new marriage if she wants him, even if it is immediate; there is no need for a waiting period. Her guardian renews it for him with a new mahr. There is no harm with repentance and seeking forgiveness. If she does not want him, he separates from her with one divorce. This is the obligation, and this is the correct of the opinions of the people of knowledge in this issue. Yes.