Musannaf Ibn Abi Shayba 9:1631

Abu Khalid narrated to us, from Sa’id, from Qatadah, from al-Hasan and Ibn ‘Umar, they both said: If he accuses her of adultery before he has consummated the marriage with her, he performs the *li’an* (oath of imprecation), and she is entitled to half of the dowry.