Musannaf Ibn Abi Shayba 27:392

Muhammad ibn Bishr al-‘Abdi narrated to us, from Mis‘ar, from ‘Abd al-Malik ibn ‘Umayr, from Musa ibn Talhah, who said: ‘A’ishah said: “‘Uthman was the most chaste of them in private parts, and the most connected of them in ties of kinship.”