Musannaf Ibn Abi Shayba 3:4813

Waki' narrated to us, he said: Isma'il bin 'Abd al-Malik narrated to us, from 'Abd al-Karim Abu Umayyah, from Mujahid, he said: "That I pray the 'Isha' prayer before the twilight disappears is more beloved to me than that I sleep through it, then pray it after the twilight has disappeared in congregation."