It was narrated from Ibn Shihab that Ubaidullah bin Abdullah told him that his father said:"The Messenger of Allah joined Maghrib and Isha with no (Voluntary) prayer in between them. He prayed Maghrib with three Rakahs and Isha with two." And Abdullah bin Umar used to join them in like manner until he met Allahm, The Mighty and Sublime

English translation · Sunan an-Nasa'i