Musannaf Ibn Abi Shayba 9:819

'Abd al-Wahhab al-Thaqafi narrated to us, from Khalid, from Abu Nadra, from 'Abd al-Rahman ibn Abi Layla, who said: I witnessed 'Umar [ibn al-Khattab] regarding a missing person whose wife had remarried, [deciding] between her and the dowry which he had driven to her.