Musnad Ahmad 3:94

Isma'il narrated to us, Ayyub narrated to us, from Nafi', from Nabih ibn Wahb, who said: Ibn Ma'mar wanted to marry his son to the daughter of Shaybah ibn Jubayr, so he sent me to Aban ibn 'Uthman, who was the commander of the Hajj season. I came to him and said to him: "Your brother wants to marry his son, and he wants you to witness that." He said: "Do I not see him as a crude Iraqi? Indeed, the one in the state of Ihram does not marry, nor does he give in marriage." Then he narrated the like of it from 'Uthman, attributing it to the Prophet (marfu').