Musnad Ahmad 1163:33

Wahb ibn Jarir narrated to us, he said: My father narrated to us, he said: I heard Abu Fazara narrating from Yazid ibn al-Asamm, from Maymunah, the wife of the Prophet, may Allah bless him and grant him peace, "that the Messenger of Allah, may Allah bless him and grant him peace, married her while in a state of non-ihram (halal), and consummated the marriage with her while in a state of non-ihram (halal). She died at Sarif, and he buried her in the shade (zulla) in which he had consummated the marriage with her." We descended into her grave, I and Ibn Abbas.