(4) باب الإحرام وما يتعلق به
'Uthman bin 'Affan (RAA) narrated that the Messenger of Allah (ﷺ) said:
"A Muhrim (one in the state of Ihram) must not contract marriage, nor help others contract marriage, nor get engaged to marry." Related by Muslim.
Reference: Bulugh al-Maram 733
In-book reference: Book 6, Hadith 26
English translation: Book 6, Hadith 752