Maliks Muwatta Book 20, Hadith Number 71.

Section : Marriage in Ihram.

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 Ubaydullah sent a message to Aban ibn Uthman (who was amir of the hajj at the time), while both of them were in ihram, saying, “I want to marry Bint Shayba 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 ibn Affan say that the Messenger of Allah, may Allah bless him and grant him peace, said, ‘A man in ihram should not marry, or give in marriage, or get betrothed.'”