Musnad Abu Ya'la al-Mawsili 150:444

Ahmad ibn Mani' narrated to us, Ya'qub ibn al-Walid al-Madani narrated to us, from Hisham ibn 'Urwah, from his father, from 'Aishah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever prays twenty rak'ahs between Maghrib and Isha, Allah will build a house for him in Paradise."