It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings of Allah be upon him) married Sayyidah Maymunah (may Allah be pleased with her) while he was in the state of Ihram.
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 2200
Hadith Gradingحکم دارالسلام:إسناده صحيح. وقوله فى هذا الطريق : «وهما محرمان» وهم، والصواب : «وهو محرم»