Musannaf Ibn Abi Shayba 33:1466

Yazid ibn Harun narrated to us, he said: Ashras Abu Shayban informed us, he said: Thabit al-Bunani narrated to us, he said: We used to follow the funeral procession, and we would not see around the bier anyone except one who was veiled and weeping, or one who was deep in thought, as if birds were upon their heads.