مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2381
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn ‘Abbas (رضي الله عنه) that Tthe Messenger of Allah (ﷺ) married Maimoonah bint al-Harith whilst travelling when he was in ihram.
Musnad Ahmad 2393A saheeh hadeeth; its isnad is hasan]