"Ibn Ma'mar wanted to have his son married. S he sent me to Aban bin Uthman who was the Amir of the (Hajj) season. I went to him and said: 'Your brother wants to marry his son and he would like for you to witness that.' He said: 'I think he is but a crude Bedouin; indeed the Muhrim is not to marry nor have someone married'" - or he said similarly - then he narrated from Uthman similar in Marfu form (from the Prophet).
Jami` at-Tirmidhi Book 9, Hadith 33