Musnad Ahmad 1165:0

Narrated Umm al-Fadl, the wife of al-Abbas, who is the sister of Maymunah (may Allah be pleased with them both): The Messenger of Allah (peace and blessings of Allah be upon him) came out to us while he was suffering from the illness in which he passed away. He had a headband tied around his head. He prayed the sunset prayer (Maghrib) and recited in it: "By the emissaries, sent one after another" (Surah al-Mursalat). Then he did not pray again until he passed away.