مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2480
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that He did not see anything wrong with a man getting married whilst in ihram, and he said: The Prophet of Allah (ﷺ) married Maimoonah bint al-Harith at an oasis called Sarif, when he was in ihram. And when the Prophet of Allah (ﷺ) completed his Hajj, he moved on and when he was at that oasis he consummated the marriage with her.
Musnad Ahmad 2492lts isnad is saheeh]