Musannaf Ibn Abi Shayba 9:104

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Shu'bah, from Ziyad ibn 'Alaqah, who said: A man from Banu Layth proposed to a woman who was previously married (thayyib). Her father refused to marry her off, so she wrote to Uthman. Uthman wrote: "If he is a match (kufu'), then tell her father to marry her off. If her father refuses, then marry her off."