the Prophet got married while he was a Muhrim (in Ihram).
Sunan Ibn Majah Book 9, Hadith 121
← Previous Hadith that the Messenger of Allah married her when he was Halal (not in Ihram). (Sahih).He (one of the narrators-Yazid) said: "And she was my maternal aunt and the maternal aunt of Idn 'Abbas also."

Sunan Ibn Majah Book 9, Hadith 120 Next Hadith → "The Messenger of Allah said: 'The one in lhram should not get married, nor arrange a marriage for anyone else, nor Propose marriage''

Sunan Ibn Majah Book 9, Hadith 122