The Messenger of Allah ﷺ said, "A person in the state of ihram for Muharram pilgrimage must not marry, must not propose, and must not give anyone in marriage."
أخبرنا قتيبة عن مالك عن نافع عن نبيه بن وهب أن أبان بن عثمان قال سمعت
قال رسول الله ﷺ لا ينكح المحرم ولا يخطب ولا ينكح
Muslim narrated it in the Book of Marriage, Chapter on the Prohibition of Marrying While in the State of Ihram and the Disapproval of Proposing Marriage During It, no. 1409, from the hadith of Malik through this route. It is also in Muwatta (Yahya's version) 1/348, 349, and in Al-Kubra, no. 3825.