Yahya related to me from Malik, from Nafi, from Nubayh ibn Wahb,who was from the tribe of Bani Abd ad-Dar, that Umar ibn Ubaydullahsent a message to Aban ibn Uthman (who was amir of the hajj at thetime), while both of them were in ihram, saying, "I want to marry BintShayba ibn Jubayr to Talha ibn Umar and I want you to be present."Aban told him that he should not do that and said, "I heard Uthman ibnAffan say that the Messenger of Allah, may Allah bless him and granthim peace, said, 'A man in ihram should not marry, or give inmarriage, or get betrothed.' "
USC-MSA web (English) reference: Book 20, Hadith 71
Arabic reference: Book 20, Hadith 775