Musannaf Ibn Abi Shayba 3:4240

Abdah narrated to us, from Mis'ar, from 'Awn ibn 'Abd Allah, from 'Ubayd Allah ibn 'Abd Allah ibn 'Utbah, who said: When the eyes would become calm (at night), 'Abd Allah would stand (for prayer). I would hear a buzzing sound from him like the buzzing of bees, until morning came.